I've experimented with the quickenings a lot, and reshuffling definitely takes more time than anything else. You can do a hit on like .01 seconds if it's after another hit, because the options appear on the screen for the next hit a split second before the timer actually starts counting down, so it's just a matter of pressing the button quickly. But reshuffling takes .25 seconds minimum, plus however much on-the-clock time you take actually reading the options that have been shuffled up.

I'm not trying to convince you that it's doable. Otherwise, I wouldn't be talking about how slow the quickenings are, and how hard it would be to do with a strategy focusing on quickenings. I was responding to where you said "You can't beat the game at that time limit, unless you skipped all cutscenes, one-hit killed bosses with Quickening chains (30 or more, mind you), and had a perfect enemy distribution." by pointing out that the quickenings actually slow the player down.

It'll take me a while to attempt, because I'll have no chance of success unless I do a regular speed run first, in order to plot a course through the game.

But in a couple of years, I guarantee you that FF12 players will be attempting and completing harder challenges than this, like the FF8 challenge where you can't gain any EXP for the whole game, or use invincibility items.