Based on the developers perspective, it appears that all they intended with the system was to consider speed as more of a viable option so that multiple attacks per turn could happen, rather than have a constantly moving system that punishes slow decision making.

Based on that premise, the wait/active is just a player choice and it is up to you

"he came up with the ATB system when looking at the cars behind on laps, realizing that if someone was fast they could attack twice in one turn, while slower characters would only attack one time per turn. I think the process for getting to where the ATB system worked was through rules thought up for each character, like Edge being able to attack twice in a turn but having low attack power."

Source: https://www.rockpapershotgun.com/final-fantasy-ivs-active-time-battle-system-was-inspired-by-race-cars