For me at least if it really is just about timing (hard to believe but I'll roll with it). I guess for me A,A, A+Z just makes the timing "natural" for me. I feel like I'm just spamming the button presses and it always stops providing the first 2 punches hit. Whenever I try to do it with just A I fail like 90% of the time. I guess using A,A,A+Z forces me to concentrate enough somehow to make the timing just fall into place. I'm not saying A,A, A+Z is the best way, but you should use whatever makes your internal timing work the best.
And Jona you really shouldn't make any sort of instruction video if you can't match the speed of the exact same move in competition, let alone be able to do it consecutively. It's understandable if you like making videos and want to put yourself out there. But you should at least get consistent with what your learning first before trying to showcase it, unless you have a problem doing it yourself and want help.