Pancake work

In pancake work (SE2, SE16-20) is it more important to open the straddle as much as possible, or to open less but increase compression (maintaining APT)?

In SE2 (standing pancake) what is the active part of the stretch, compressing, actively trying to open the straddle even more, or what?

Finally, in SE4-5 (vertical frog) should I get the hips as low as possible first, with the hip of the straight leg on the floor, and then open the knee on the bent side as much as possible, or first open the knee as much as possible and then bring the hips down? Where should I feel the stretch?

On SE2: open the legs approximately at 90-100° then aim to improve compression , the more you can hold the APT the better it is. On the floor variation when reached the pancake on 90-100° and the SE16-20 required range of motion you have to increase the straddle of 25-30° and begin again to master the required rom.

Se4-5: second option, before open the legs then move down gradually. it has the same idea of sumo squat, you cannot put stress on correct muscles if you do not have already mastered a decent straddle.

Thanks Alessandro, that's very useful.