If the combat order is P1 P2 P3 P4 E1 E2 E3 E4 E5 E6 (which it almost always is, with almost zero exceptions outside of bosses taking the first slot) and you want P4 to setup something for anyone else, then saving your AP results in almost the same end result as delaying your turn. The difference is this way you have more AP.
Even if the order is E1 P1 E2 E3 E4 P2 P3 E5 P4 E6 then there's little reason to delay P1 for P4. Only E1 will be different if you delay versus save your AP. However delaying P2 and P3 makes sense. The problem is that this situation is basically unheard of.
P1 is my fighter. P2 is my healer. P1 gets hit hard during the turn and ends up with a status effect and 2hp. If you had delayed P2 you can cast heal before the status effect procs and P1 dies. If you pass P1 goes first and dies.
I'm in that situation frequently, if not so dire. If your fight and healer are in a different order you might not see this that often.
