One way this happens is often to do with speech, or conversations. In certain circles, such as pen and paper role playing or comics, it's known as "Speech is a free action". This essentially means that a bomb could go off in 5 seconds, yet they could monologue for five minutes and still have time to disarm the bomb. Now, the example of 5 seconds versus 5 minutes stretches it to a point where anyone can notice it, but more often than not it's much more subtle than that. The time it takes to swing a sword, for example, versus say even one sentence between blows. If you were to stand up right now, grab the closest stick or pole, and swing it a couple of times, you'd find it hard to say a sentence at the same time, much less between swings. This is also especially true of writing where we get to hear their conscious thoughts.
Another subtle way that conversations are affected is by how they get interrupted. Rarely do we find a conversation is interrupted in the middle of a topic. Let's say two good guy characters are talking about the weather. They'll manage to talk about today's weather, tomorrow's weather, and last week's weather, but it's not until they start talking about last month's or last year's weather, and we the reader start to get bored with talking about the weather, that they get interrupted by something, whether that's a bad guy blowing up the building, or space ship, or someone else entering the room. Go back and read a few books where you remember conversations getting interrupted, and then ask yourself if there was anything more to actually be said about the topic that was interrupted. If the answer is no, chances are the author used the interruption to finish a conversation they weren't sure how to continue. It's not hard to do that without even realizing it, though, because it's so easy to see that plot device as poetic or humorous when we think about the pie in the sky imagining how a scene plays out.
My personal pet peeve, regarding conversations, is how two characters will frequently say each others name during the conversation when they're the only two possibly talking to each other. For example, "Good morning, Bob" is okay, but when the conversation has been going for a few sentences and they say "I know you like that lady, Bob" it gets overused. Absolutely no one that I know uses someones name in conversation, except maybe (maybe!) as part of the greeting, when there's only one person they're talking to. They absolutely do not use it every other sentence. I know some writing workshops may recommend using character names as part of conversation in order to introduce them, but you have to be very careful to only do it when you as a person would actually use their name when talking to them. Two characters that have known each other for years just wouldn't do it.