I was thinking...
Currently, there is possibly bad outcomes, so I don't use them in a fight. And while there is mostly temporary outcomes, I don't find it interesting to consume-test them outside of fight. And while I never find the same twice in a game, I see no point in testing them for later identification.
But if all Mystery Circuits were guaranteed to be both good and temporary, it would make for some fun outcomes. Like "oh, I'm faster... against Wall Master. Nice ><" or surprise damage boost, or surprise defense/immunity, etc. This way, they would be usable during a fight and the player would have a beneficial boost at the cost of adaptation to the random effect. Maybe mysterious circuits could even be always mysterious; one type of consumable with a random effect. That kind, I would use. Or maybe if the bad effects were still temporary, a little bit rarer and manageable in a fight, like half speed, half damages, depletes shields, etc, I would still try them in a fight.