P4A All-out attack mashing

[Critz]

So, I recently learned that in P4 Arena games, the All-out attack overhead into blowback (AB > mash AB > D) changes properties if you manage to mash AB enough amount of times during the short AoA timeframe and then follow it up with a D in time, enforcing a Fatal Counter and extended hitstun (as opposed to AoA into C launch button, which always fatals).

My problem is, as you might guess, the mashing part. Getting all 17 hits and then hitting D to blow the opponent back in that extremely short time frame proves to be borderline impossible for me - I play on default Dual Shock 3 and mashing A+B eight times into D requires great physical effort from me (a more distant pad grab to optimize thumb mashing speed and absolute focus so that I won't let up the pace for even a splitsecond) as well as great luck in picking the time to hit D (so I won't hit it too early and not max my hits, nor too late and end up not launching), just to have a slight chance at suceeding (which I'd estimate at 10% chance if I put maximum effort, 0% if I let up ever so slighly).

As you can see, the whole mash to combo deal not only feels extremely pointless and spiteful on Arcsys's part to me (I can't see a single benefit of the mechanic), but also difficult enough that I wasn't even aware that it is a thing until I tried a 10-run Junpei combo recently - 5C CH > AoA~D Ender > 5B > 2B > J.B > J.B > J.236B (1 hit) > {OMB > J.B > J.B > J.236A} > 236236D~A to be precise (worse still, I've heard that the first game actually required two hits *less* than Ultimax for AoA~D to FC, so someone must have *liked* the idea of making players develop carpal tunnel syndrome). That brings me to my questions:

-Is the proper AoA~D usage a key part of gameplay in general or some characters in particular, and which characters can do well without it? I've mentioned that Junpei 10-run combo that needs the fatal counter to make it possible to connect 5B, but do other characters have similiar corner combos that are particularly important for their game plan?

-How do YOU handle that mashing part? Is your hand trained enough that you just naturally manage to hit A+B 8 times and then D in the required time frame well enough to make AoA~D attempts remotely practical? Or do you have some trick up your sleeve, like playing on a stick or some specific gamepad, different pad grasp, some useful macro or turbo fire button (I actually tried turbo fire on my friend's gamepad, and while the timing of the D hit is still a little strict, it helps immensely by removing the mashing part, so I might get myself one too)? Or something else that I didn't think of?

Any feedback will be tremendously helpful, so thanks in advance.

[heavymetalmixer]

After your AoA hits, mash A+B 6 times and then the ender, it isn't easy, but you have to get used to it.

[Speakeasy]

You can try setting a button to A+B and see if that helps.