‘c’ and ‘t’ should definitely be hit with different fingers if you do touch-typing. But with one hand, that's true.

I just recorded myself typing it a dozen of times, and it always goes as:

F - Left index U - Right middle N - Right index C - Left index T - Left middle I - Right middle O - Right ring N - Right index

I usually generally follow zones while typing, but for frequent words like this I tend to break it, which mostly make sense, like using middle finger for U to free index finger for N, and then moving it one over for a quick IO without lifting the index from N), but then that CT thing is a decades-long ingrained thing that I didn't even realize how weird it was until I looked closely at it. It reminds me of that thing that bothers me on my other kb which is ortholinear and I always struggle in games with it because I can't press 2 while holding Shift and W at the same time. On normal keyboards I use ring fingers and slightly twist my wrist clockwise, but on ortholinear it's not there, and it's actually easier to use index finger and twist the other way, or roll middle over without lifting, but it's very hard to break that habit.