Wouldn't the total amount of use you get out of your shirts count? So while only using any single shirts once a year will easily get you decades of use out of them, it's not really beneficial or is it?
Or do clothes get better with resting in between uses? (I heard leather shoes do benefit from a rest.)
I buy all cotton, and organic if I can.
Proper and not too-frequent washing can help.
Clothes washing itself as well, though I believe to a lesser extent.
Sufficient vs. excessive laundering helps greatly.
https://www.sciencedaily.com/releases/1999/08/990831080157.h...
However, there are also trade-offs with convenience. Basic cotton t-shirts are so cheap, that it can be worth it for some people to not bother taking care of them and just replacing them more often.