After about on hour or so they start to irritate me, after 2 hours they hurt bad enough that I have to take them off. They are the only Oakleys I've ever had any problem with. Considering they took 4 years to design them you'd think they would have gotten the whole fit part right. In any case they look too badass not to wear, So I'll just choose another pair if I think I'm going to be wearing them for hours on end.
I have a big head...in fact the Pit Boss was designed for big heads, has to have been because it just fits me. With that said, yes I had the same problem...and after consistently wearing the PB for a couple months it went away. Even after taking breaks from ownership it never came back...at least in my case my nerves or whatever there got used to the pressure
And an additional factor? The frame type. I've owned the Polished Black versions and the Matte. First the Matte frame is lighter and second the weight of the polished frame seems to increase the head pain.
I've been wearing my Pit Bosses for over a year now, but usually on and off, as I move from outdoors to indoors and then back out. Liking the PB fit more and more. Used to think they were too tight. Not anymore. Guess one's head somehow adapts to the PB?