Thanks everyone who replied. I know every unit will be different, but it helpful to hear from several people who have worked where you're short staffed! It sounds like it's very much your choice to work OT or not.

Hi all, I'm a current Nav Canada applicant. I've been able to find a lot of good information here and other places as far as what to expect with an ATC job. I'm grateful for all this excellent info! However, one question I have not been able to gain clarity on is how much mandatory overtime must be ...