I'm on week 4 of 8:30 to 1am.. it's pretty devastating on the body...
If your NOT self-employed, draw a line or make sure your getting paid, I used to pull long shifts because I felt it was the norm.
I never got compensated. Once I was moving on a Sunday, hit the office at 8pm till 3am, took the next day off to carry on unpacking, was forced to take a leave day. I once had an accident because I just landed from an international flight after a week of 18 hour days and a further 2 days with no sleep, the excess was my problem, not theirs. Another instance after 8 days of travel I clocked R1000 in fines just to get home and hit the hay. My cost not theirs.
Most people will screw you over, putting in extra effort where needed is fine and it shows commitment, do not let yourself get screwed over though. If your asking it means your putting in more than an acceptable amount of overtime with no compensation, raise it and draw a line.
If you want to flip it to a companies perspective, hiring an employee (depending on industry, I will reference mine) is an expensive and time costly exercise, paying you R5k of overtime is pocket change to what it would cost to replace you. But, if you don't raise it, they don't actually know.
You may not qualify for overtime, if you hold a professional position (it's in the labour law) but if its an issue, raise it... if you don't the company is oblivious and you feel screwed which affects your work and attitude and they think everything ok.