I'm half time as an engineer. My current company is tiny- almost no benefits, no hr, etc. I am 50% time, get 50% of a full time salary, and am not on call, but I make myself available for stuff when possible. I don't work any specific days/times, I set my own schedule.
When I was 60% at a big company, it was 3 set days a week, 60% of full time salary, and I paid a bit more for health insurance. That was more of a set schedule, and I didn't usually have to call in to anything on off days.