I usually work weekends

Sometimes I'm obligated to come in on a Saturday which sucks. Yes.

Everyday even on holidays

In cases of emergency and due to international timescales it is sometimes necessary.

If I'm working on a weekend something bad has happened

I often have to for teaching, but I always do that from home. I make it a point to not work in the lab on the weekends though. It's too depressing to be there on the weekend

Used to work on weekends too most of the time, this wasn't healthy tough.

Yes. When the deadline is approaching I have to work as long as I can. In January I worked 230 hours because of an approaching deadline.

Not for awhile