I didn't show up on the first Saturday when I started my Ph.D. program. Next Monday, a professor from _another_ department stopped by my desk to tell me that as

I didn't show up on the first Saturday when I started my Ph.D. program. Next Monday, a professor from _another_ department stopped by my desk to tell me that assistant professors and Ph.D. students are expected to be there at least six days a week. Then he gave examples of a few professors who were there even on Sundays despite being tenured. Tbh, I was so poorly paid that going to the university on Saturdays wasn't so bad as they had better air conditioning and heating compared to my apartment!