It's a tough one @karabreanne19. I have pulled a number of 12, 14 and even 16 hour days, and it takes a lot out of you. There is certainly a built-in perception of "that's the industry, deal with it", but as upcoming filmmakers, I feel it is our duty to challenge the status quo. In Australia, there is not a single other industry that will tolerate anything more than a 12 hour working day, due to strict fatigue laws. Some areas do require the occasional overtime (emergency services, truck drivers), but these are generally not considered the norm and are compensated with major overtime penalty rates.
To my knowledge, union shoots in the US do legislate 12 or possibly 14 hour working days, with overtime after that, and for a lot of filmmakers, this is what makes filmmaking so lucrative. But, there is a huge cost to it; for productions, it costs as much to go over 5 hours, as it does to schedule a whole new day; for the filmmakers, this can put a huge strain on their mental, physical and emotional health, and can stress relationships to breaking point.
There will be days were you will be required to put in the long hours; that is part and parcel of the industry. You may not have the location, crew or equipment for any longer and you just have to smash it out. But doing day after day after day of long hours will put an unacceptable strain on the crew and lives have been lost as a result.
Safety should absolutely be the number 1 priority on any set; there is no scene or shot that is worth ANYONE's life and I think that should extend to the hours people work. There is a reason fatigue laws exist and it's to ensure the wellbeing of workers. How would you react if your production required someone to put in a week of 16 hour days, and on their way home for a shoot with a 4 hour turnaround, they crashed their car killing a themselves or their family, how would you feel?
In an entry level position, it can be tough to speak up, and frankly, you will have no sway over scheduling and would probably be fired if you made an issue of it. But, it is my hope, that as the next generation of filmmakers advances and begins to take on those lead roles, they will be able to challenge the status quo and understand that at the end of the day, we're only making movies; it's not worth somebodies life.