Since a fixed time stage isn’t scored as HF you probably won’t see many regular stages with a par time. Standards and speed shoots can use fixed time.
I just like mixing up stages a bit and letting the competitors see things they don’t normally do. Speed is important on any stage but when you measured against a fixed time it tends to mess with the usual. There are no mikes or FTSAs, just NPMs, overtime and extra shots, and extra hits.
I ran into a fixed time stage at A5 for the first time and didn’t have a clue as to what it was. It would have been easier if I had been introduced to it at a L1 match first. That’s my theory and I’m sticking to it, after all, they were crazy enough to ask me to be MD.