For a shirt, it would be once.
For a t-shirt, sometimes I might wear one after getting home from work and then go on to wear it again the next day (so what's that, 1.5 days
) ... especially in the cooler months.
"Do not force others, including children, by any means whatsoever, to adopt your views, whether by authority, threat, money, propaganda, or even education." - Ven. Thich Nhat Hanh
"Whether I were to preach in brief, Sāriputta, or whether I were to preach in detail, Sāriputta, or whether I were to preach both in brief or in detail, Sāriputta, rare are those who understand." (A I 333, Sāriputtasutta)