In the comments, Michelle asks,
Great post! I have a question, though. It doesn't really relate to your topic, but the topic reminded me of this.
What do you do when you have long passages of time you're skipping over? Do you summarize it? Make a note that so much time has passed? Or do you just jump right into the action and slip clues into the text that tell the reader time has passed?
Actually, Michelle, this is on topic if we define our current topic as, "Theresa rambles about exposition, etc." The start of scenes is a common place to rely on exposition to transition a reader to a new time and space. This can be done with a subheader at the top of the scene, such as--
January, Okanagan Lake
This tends to work best when it's already been established that the protagonist will be located at this spot for some reason. Maybe he's searching for Ogopogo, the famous sea monster of Okanagan Lake, so the reader has been prepared for him to reach the shores. This kind of quick, non-narrative transition allows the text to zoom forward without a lot of set-up at the start of the scene.
There are other times this type of transition will work. Maybe you have a multi-thread plot and keep shifting the reader between the pieces. Then the subheaders can help the reader track which plot thread is which. The current scene is Larry searching for Ogopogo on Okanagan Lake, and the next scene is Jessica searching for Nessie at Loch Ness, and the next scene is Bonita in a secret science lab trying to hatch a lake monster egg. The three of them are racing to produce a live lake monster, and the plot shifts freely between the three threads, and the subheaders help the reader track it all.
In any case, some authors avoid these kinds of headings because they don't want to clutter the page, and there might be some good arguments against using these kinds of subheaders. Much like chapter headings and title/author headings, these pieces contain words that help identify something in the story but are not really part of the story. So they might serve as a distraction to the reader. If you think this isn't an issue, consider the reason we put last name/page number headings on the upper RIGHT corner of a manuscript. This keeps us from turning the sheet and processing the heading as the first line of text on a new page, which can break the flow of the narrative. Scene headers are not quite as disruptive, given that they're inserted in breaks in the story action, but they are still external intrusions of a sort.
So that takes us to narrative transitions at the start of new scenes. How much is too much? Can you ever skip it all together? I have a rule of thumb for this, but it's one of those things that can be hard to apply. But here's the basic idea. At several points over the course of most manuscripts, we will have to effectively press a reset button for the reader. The protagonist or another character will have changed enough, or the plot or setting will have changed enough, that we will need to create something like a touchstone for the arc within the text. Those touchstones can serve like transitions in to the next big piece of the plot. The bigger the changes, the greater the need to press the reset button. The greater the need, the more text you might need to re-orient the reader. But that's by no means hard and fast. Sometimes it's possible to re-orient the reader with a very quick transition. That's why I say this general rule of thumb is hard to apply. It can be difficult to gauge just how large a touchstone you need to create.
But as with all exposition, you will usually be better off minimizing the length as much as possible. Let's say, for example, that our monster-hunting friend Larry has been searching for Nessie for years and only just learned about the existence of Ogopogo. His goal has always been to find Nessie, so traveling to Canada would be a big change that might not support his original goal. Why would he do it, then?
Maybe there are scenes in Scotland with his band of Nessie hunters in which they debate the matter. Maybe Larry is opposed to going, but the group votes that one of them must go. Maybe he wants to go, but the group scorns him and tries to prevent his departure. In any case, the moment when Larry arrives on the shores of Okanagan Lake will be the moment when his quest has changed. Depending on what came before and what follows, you might need a small touchstone or a large touchstone. But, unless the change has been adequately prepped in preceding scenes, you will probably need a touchstone. (This is also partly dependent on how much has happened since the last touchstone. As I said, this analysis is very book-specific.)
But let's say you're not worried about pressing the reset button and reorienting the reader. Let's say everybody already knows why Larry abandoned Nessie for Ogopogo. In that case, a simple clause indicating time and space might be all you need.
Larry shielded his eyes against the bright spring sunshine glinting off the surface of Okanagan Lake.
Boom. One sentence, all action, no exposition, and yet we know the time and place after reading it. Or maybe you're a traditionalist and prefer an adverb clause.
When Larry reached the daffodil-covered shores of Okanagan Lake, ...
This is an expositional transition, and it's brief enough that it won't drag on the pacing. In ten words, we get the new time and space. It might be enough information.
What you probably want to avoid, unless it's strictly necessary for reader comprehension, is a long run of exposition like this.
Okanagan Lake was a deep lake with two islands. Because of the temperate but rainy climate, Larry knew he would need a different equipment and clothing. He shopped for two days to gather waterproof fleece pullovers and windbreakers, new rubber boots, waterproof matches, and a supply of his favorite Scottish tea, which he was pretty sure would be rare in rural British Columbia. The hardest part was deciding which camera equipment to pack. He only wanted to have one suitcase and one carry-on, but the equipment took a lot of space. But he would only be there a few days. He did pack some extra socks in case it rained on the boat and tossed in his favorite copy of a Douglas Adams book to read on the plane. Maybe this trip would be a complete waste of time, but at least he arrived in Vernon with everything he needed.
These kinds of blocks at the beginnings of scenes are almost always worth cutting or trimming. Notice how much of the text summarizes things that happen in the moments between the last scene's ending and this scene's beginning. Shopping and packing are usually dull events, so we wouldn't want to convert this passage into actual scenes if nothing dramatic happens. But if they're dull, guess what's also going to be dull? This info dump of a transition. If for some reason we need to plant the notion that Larry packed specially for this trip and bought new gear, we can reference it in an adverb clause transition.
After two days of shopping and packing, Larry arrived at Okanagan Lake with more than he probably needed.
And then, if the extra pair of socks is necessary to the action of a future scene, you can probably just have him change his socks then and there without a lot of explanation. If it's relevant to character or theme, maybe you would have Larry think about the cautious packing when he changes his socks.
He stripped off his sodden footwear with silent gratitude that he had remembered to pack extra socks.
But this depends on whether the detail is the kind of detail that needs to be set up in advance. Packing extra socks for outdoor adventures in a wet climate is probably not remarkable enough to require set-up. But again, this is one of those things that is highly book-specific.
So, to answer your question: Depends on the book, depends on the scene, and depends on the author's goals. But it's usually best to keep start-of-scene transitions brief.