But it's an empirical question, not an "extrapolate from my experience" question. You can see this most clearly by considering that the first two minutes of every game, every half is played exclusively by people who haven't gotten into the flow of the game yet. So are the first minutes of games sloppier than the midpoints? Statistics from the NBA say: Yes, but not that much. So there is a real effect about flow and sloppiness, but that's five guys on the court who are out of flow. What does that say about one guy?
ChatGPT says there's no clear data either way in the NBA (which is the usual touchstone for analysis because the data is so much better) as to the effect of playing time increments. The studies are inconclusive and all over the place. Which makes sense because this is a very hard thing to measure: you're talking about players who are indeed worse than the starters (or else they would be playing more) and the # of minutes of data isn't very large because they aren't playing many minutes; and often the reason they play is that is something is "off" about the game -- i.e. injuries, foul trouble, etc.
I would say the real effect is not having a defined role. If you're playing consistently 15 mpg, then you know what you're supposed to be doing. Your teammates know. If you're playing 2 minutes, your role is probably unclear. But that's also speculation and not something I would assert.
In any event, Nickel played 12 minutes against Syracuse and 10 minutes against Wake in the spring of his freshman year. He was pretty bad against Wake. Against Cuse, he didn't do much. Hit a three, got a steal and an assist. Not bad, but not good.