[Just Jim]

It's fairly common for line cooks to not take breaks, or not take as many as other professions.
Occasionally they are denied breaks, but that should be rare these days.
But many just don't take them.
They want to get the work done, don't want to lose their rythym.
They are also the ones who usually rise up through the ranks.
Not for their not getting breaks, but for the overall attitude that is shown, foregoing breaks just being one aspect, that "get the job done at all costs" attitude.

I have run into situations where I try to get a cook to take a break only to have them resist.
I finally tell them that they are officially on break....if they wish to spend it cooking next to me, that's their business.

Food service is somewhat unique....in a typical 9-5 job, you could usually take your breaks every 2 hours.
In a restaurant, customers don't come in according to that schedule.
You might get a couple of breaks close together, or at the end of the shift.

When I was rising up (once I got my head on straight), I wanted to spend as much time gaining hands-on experience.
Before that, I was just looking for an excuse to not work.

Basically, it's an individual thing.
You want a break?
Take one.
If they don't let you, you have a decision to make.
I won't bother to spell it out for you.