Working overtime now and then is perfectly normal and, in a normal company, it should not be an excuse to get more money. There are days like that and you're part of a team, so pull your weight and everyone will appreciate.
However, if working overtime becomes a regularly repeating occurrence, then it should definitely be paid for at least two reasons : 1) you are in effect working longer weeks regularly so you should be compensated, and 2) the company needs to understand that it might benefit from hiring another person to lessen the load on the others.
My stance on overtime is simple : if you tell me no overtime is paid, then I'm not working overtime. And don't come and blame me for projects that are late, you're management ; you're supposed to be aware of my workload and find solutions to lighten it if necessary.
Reminds me of the time I was in a certain company with the manager always coming to me with new urgent things that had to be done right away. After the fourth addition I looked directly at him and asked whether it was right away before the thing for the Director, or right away after that ? I then shoved the list in front of him and told him that I needed an order of execution. He blustered his way out of that, but I didn't see him for the rest of the day. Thankfully I was not long at that company.