No it isn't; you don't get anything more done, unless it is for one (maybe two) weeks out of 8-12 weeks, and even then it is limited to about a 15-20% increase for those weeks.
Speaking as an employer who needs to get an "honest week's work" consistently out of my employees, I discourage overtime. There are a few exceptions (deadlines must be met, sometimes people have to chip in more to cover for others on vacation our overloaded, etc.), and we pay straight hourly wages for salaried employees earning less than $80k. The big exception is entry level engineers, who generally need to put in more than 40 hours per week in order to cover both trip aiming and "working" time.
The alternative is hiring and firing, which doesn't really work for either side.
If we are forced to pay time-and-a-half overtime for an entry level engineer (more importantly is the idea of them being non-exempt-- which means they need to have scheduled breaks and lunch), we will never hire an engineer without appropriate experience in our field again. Young professionals being treated like factory, retail, or unskilled labor destroys a professional work ethic. Professionals manage their own time, take breaks when they need to, finish their work, and don't use a time clock.