Unless you're in a really dysfunctional startup, the employees who voluntarily jump in after-hours to fix OC issues are going to be very quickly compensated with raises and refresher option grants. Far better payout generally than a few bucks of overtime.
It becomes really obvious who is holding the company together and who is coasting, relying on the "senior" (ie, anyone who puts in the effort) engineers to keep the ship afloat, and in a highly competitive engineering market, that will definitely be reflected in equity comp.
I respectfully disagree. I did exactly this for a number of years. A colleague (and is now friend since we've both left said company) made it clear he would not work overtime without compensation (and never did), but his day-to-day work was excellent. He knew he had a skill they required, and was good at it (and our skill sets were the same).
Our careers both grew at about the same pace for four years. He became known as the go-to guy for green-field projects, while I was the guy you could put onto over-budget tight-deadline projects to rescue them. I worked a lot of weekends for my troubles, and I always envied how he ended up on the "fun" projects. I learnt a lot from him. As a professional, some self respect is required, or you will be abused.
The problem with informal "people will notice" reward schemes, even when administered well (and don't take that for granted, it's easy for them to become popularity contests!), is that they encourage bad work-life balance among more junior employees. If you regularly have people popping up at 10 PM to fix things, and you don't have any formal recognition of the fact that they've gone above and beyond, new hires who want to get ahead will learn that working late into the night is the way to do that.
Going above and beyond what your fellow humans are willing to do is a pretty tried-and-true way to get ahead, whether you’re working for yourself or as an employee.
Visible to who? Certainly the request to work outside of their normal schedule, and the report that an issue was resolved are seen by more than just the person responding to the request?
It becomes really obvious who is holding the company together and who is coasting, relying on the "senior" (ie, anyone who puts in the effort) engineers to keep the ship afloat, and in a highly competitive engineering market, that will definitely be reflected in equity comp.