Exactly right, every situation is different, and it is your opponents play that
tells you what you should do.
Do you have the nuts no matter what happens on the river (100%
equity)? Obviously you want to extract as many chips as possible. Giving your opponent one more card to build a hand cannot hurt you. Betting and getting a fold is the last thing you want. As already stated, this is especially good if your opponent will bet for you. For me I will ALWAYS right size (maximize my bets to guarantee a call, whether it be for the turn and river or just the river. Again there is no point in getting a fold. If he will call an all-in then go for it. If an all-in will get a fold, then don't do this. If a minimum bet is the only bet that will get a call, then I guess this is your best bet.
or
Or is it only the nuts based on the board at the moment? A nut flush is beat by a boat and boats generally happen on the river. An A high flush has a ton of equity (>85%), but isn't the nuts until we see no paired board on the river. A player with 2 pr or a set has 10 outs to a boat+, which is about 20% chance. So, technically you do not have the nuts yet. Based on your opponents play are you worried about this possibility? If so, would he call a shove with a set or 2 pair? In this situation, a small value bet has a small amount of risk. Obviously, a large bet may win now, and miss out on some value. relative stacks also tell you a piece of this story...and on and on and on.