Too much focus on looking for external business "opportunities" & too little focus on "core business". You just live with it & I doubt it will change much any time soon.
We work in groups that control multiple sectors - initially you hold one rating but gain more over time until you hold all in your group. What you work generally depends on who is due for a break from the console, so usually you work more than one sector in a shift. Also we combine sectors when it's quiet.
Overtime is mainly a whole shift to replace someone who has called in sick or a blank shift in the roster, so you're getting called in on your days off. Occasionally you do an extra hour or two at the end of a shift if there's something out of the ordinary like bad thunderstorms.
It's certainly not a job for everyone but if you don't try you'll never know. Do the GA night if you can.