When I said turn 30-40 on my previous post I meant in a 1v1 so 15-20 moves.
It really depends. If I have a move that absolutely depends on opponents wits I'll usually count but most of the time I just try estimate and guess the best I can. Sometimes I just straight up forget, if I don't see a possible move for me that requires counting. Also, I tend to count wits on the games where I've had good vision because it's so much easier haha.
I just played a 2v2 with Torbreck where I didn't realize we could keep pushing. The opponent had so many units in front of his base it looked daunting. Torbreck reminded me that he didn't have a wit spot for the last couple turns and it would be fairly safe to go ahead and attack rather than back up and defend the attack from the other opponent. We counted wits and he was right. I didn't feel too bad for not seeing the move though, Torbreck is an outwitters God.
I count wits on sfi a lot because the vision is so easy to have, and it's a smaller map. If I'm up against scallywags on sfi I'll count wits every time. Have to keep an eye on when they might be spawning that bs and hit at the right moment.
I guess I could have not written all of that just now and summed it all up by saying: sometimes I'll count wits but it's situational. Probably 1 out of 3 games I'll count past the first 10-15 turns.