Need to have a reckoning of sorts re: how many cool tabletop tales centre around "I rolled a 20 and then something cool happened". More than ever I feel like players should be able to invoke that neat narrative/mechanical effect on demand, albeit with some sort of rare resource, but at the same time I don't want to completely do away with being able to do it randomly because that can be pretty fun in and of itself
I do have a very basic "I don't want to crit on this roll, let me do it later" mechanic which I tend to sloppily port to every d20 system I've ran a campaign in. In some forms it meant carrying a +1d6 bonus with you until such a time as you wanted to deploy it. In others I simply stated that you could "bank" the natural 20 and announce the critical when you actually needed it. I don't think there's any kind of simulationist explanation for either of those but I can't say I care very much
Conversely I've got an "Exploit" system that I keep coming back to across multiple projects: the notion that a player's critical failure is less their fuck-up and more a sign of the dangerous skills of their opponent. A much more vague, abstracted, narrative way of saying "the enemy does something gamechanging in response".
And of course it should work both ways. If the hostile trooper rolls a 1 in melee with the berserker, you're damn right the berserker will suplex them as a free action. Rules of nature
Generally I just don't like the idea of a super-expert-specialist failing at a task 5% of the time, but I can buy that 5% of the time their opponent is ALSO some kind of super-expert-specialist who can exploit the narrowest of openings to even the odds
The superspy doesn't drop his pistol like a clutz, but their nemesis sure can disarm him during the climactic duel. The hacker didn't misclick, but she did finally attract the attention of the Anti-Hacker Corps that you invented on the spot.
But when the nemesis rolls their own Exploit, they're definitely getting shoved off the balcony. And the AHC will find that their database has been replaced with 300 million repeated instances of "lmao you suckers"
and this is why The Merry Band will have auto succeeding skills unique to each job