I meant that yes he travels a lot, but no that doesn't make it harder to know in which state he has been the most (or whichever rule applies in the US to determ

I meant that yes he travels a lot, but no that doesn't make it harder to know in which state he has been the most (or whichever rule applies in the US to determine in which state you officially reside) and thus to figure out where he should pay taxes.