i have a python script running through that right now to find "the shortest" and it's been burning a single core for at least 6 hours. So it looks like you are right and i am wrong ;-)

i assume my pc on a single core can do ~1billion permutations per second, this will take 19,647 millennia. AFK.

what do you think the chances are, if i let this run, that it would find a shorter solution than 625 keypresses? the naive De Bruijn algorithm popped that out in like 2 seconds.