Long time off
I worked for the US government. If you were off for more than 3 days you were supposed to get a note from a doctor. But sometimes I would be off for a whole week if I was horribly sick and never had a note.
You could accumulate sick leave. I was under the old retirement system, where saved up sick leave could count for your length of service. So I tried to use sick leave as sparingly as possible. When I retired, I had almost 1 1/2 years of sick leave saved up.