Shot cup petals should "Never" extend beyond the shot, better to be a bit shy. When the petals extend beyond he shot they are encased in the fold of the crimp, whether roll or pie. This presents a very real possibility of the wad being retarded before the crimp can open.
I have to openly admit that what you say makes absolutely no sense to me at all.
AND even tho I've a limited reloading experience with only about 500,000 behind me, I've not seen a wad that would allow even a modest length of petal in the crimp that could actually be crimped and look like something one would want to put in a gun. I've loaded maybe 200K 24gm loads in 28gm shotcups and have never seen or felt or whatever any indication of high pressure and those were close to max or max loads to start with.
If you'd care to pay for it I can supply you with any number of similar loads for pressure testing.
