In my gym, the lesson always start with 3 min of running.
After that, some time is spent on passive stretching.
The next step is abdomen exercises: something like 10x30 different variation of "high, mid, low, internal, external (!), left or right" segment of them. Some variation of pushups (not hspu or planche one, of course) will follow.
The routine is performed everytime.
In the meanwhile, I do like 15 min of dynamic stretching (quite useful if you do it everyday) and work my abs only on p-bars and such, in the end of my skill training.
Yesterday I showed the results to all winning a L-sit race (more than a minute hold), even the guys with multi-year training in gymnastics failed (because they feel cramps in the quads, something I dont experience anymore ever, thanks to specific training).
The lesson?
Dont waste your time on this type of conditioning.
The static exercise and 1 or 2 basic exercise that focus on abs are more than your body can take, IF performed well.
For example, something like L-lifts will enhance your midsection strength to level that 1000abs people will only dreams of.
Feel free to post your opinions on this, thanks