Your turn dude.
What? Ummm. Sure, I uh, guess I will go over here. No wait. Hm. Let me look at the board for a minute to figure out what I am doing next.
Couldn't you have thought about this ahead of time?!?
This is a constant conversation when playing games, especially when playing with people who are particularly slow to decide or who aren't all that interested in the game. The trouble is that people who play slowly not only make their own turn take forever but also cause issues for the next person; when the previous turn is taking forever even the most involved player will end up drifting off and forget what they had intended to do themselves. It is at its worst in games like DnD where some players really do have enormously complex choices (like a high level wizard) and some players have virtually no choice at all (like a low level fighter). It is not much fun when each of your turns takes 30 seconds and another player takes 15 minutes and it is nearly impossible to stay mentally focused on the game. Players try to come up with rules to force people to act quickly but when the game is heinously complex that will tend to leave the tacticians irritated.
In terms of tabletop RPGs I think the solution has four parts.
1. Make sure that everyone has interesting tactical decisions so that everyone feels like they are participating and everyone has to take time now and again to consider.
2. Make sure that nobody has a truly outrageous number of options so that even the hardcore tacticians can parse all of their options in a reasonable time frame.
3. Arrange the combat mechanics such that figuring out what a given effect will accomplish is easy. Figuring out what the *best* choice is should be hard but figuring what will happen if you do X should be trivial. Players should not sit around flipping through books to figure out what their abilities do.
4. Enforce some kind of time restriction. Even with straightforward choices some people take forever to decide (and you know who you are!) and it is important to make sure they have a limit. Characters don't have forever to figure out tactics so this is both supporting immersion and making things more fun.
It is not nearly so easy with a regular board game. The trouble with a board game designed to have players opposing one another is that nearly every turn people change the game state substantially because they are actively *trying* to force their opponents to make different choices. Often you can't play your turn ahead at all because there are simply too many choices to parse until your turn begins or you have nowhere near enough information to decide anything useful. Cooperative games don't have this issue because you are building something together and you really want to know what it is your partners are trying to accomplish and they want to support whatever it is you are obviously planning.
I am not convinced there is any easy solution to this issue. If people can't really oppose each other very much then you have a game like Dominion which often feels like Solitaire. If people can oppose each other in a direct way then you have a game like Settlers where people feel ganged up on. If opposing someone must be done in a indirect way like Puerto Rico then the game will totally shift with each choice and you will need lots of time to parse after every move. Obviously all three of those games are games I enjoy but all of them have different pieces of this problem at their core. Perhaps my next project will be to design a game that tries to address this in particular and see if I can find any interesting solutions.