Regarding bullpen use: teams go into each game with a blueprint for how they are going to manage their relievers that day. Among other things, the plan is dictated by recent usage / availability of the relievers, the opponent's lineup, the opponent's bench options, and recent usage thereof. Now, there are things that can affect the plan like injuries, extra-innings, etc. This allows the relievers to be prepared to the extent possible that they may be pitching each day. Many of the bullpen decisions managers make in-game are actually pre-determined, or at least thought-out, well before each situation arises within the course of a game. There are definitely some, but probably not quite as many ‘spur-of-the-moment’ decisions made in-game as we may sometimes think.