I've started a new job where my colleagues often eat lunch at their desk and stay late. I work hard, I currently have enough time to do everything I need to do, additionally I'm prone to work stress so I generally take my full lunch break to get out and clear my head and I leave at 5pm. Even though I've been told the company is pleased with my work and I always offer to help out others and do stay 5-10 minutes if I'm in the middle of something at the end of the day - I still feel a bit self-conscious that I'm always the first to leave and that my absence at lunch might be conspicuous.
Today I've found out that a colleague who takes the same attitude to working hours has been struggling to keep up with his work and that the manager has suggested very bluntly that he should be taking shorter lunch breaks and staying longer if he can't deliver in his normal hours.
It's made me feel anxious that my colleagues associate shorter hours with less work and that even though I'm delivering everything I'm asked to I might not be 'playing the game' properly. Tbh it's also riled me a bit - I saw my father's happiness swallowed up by an all-consuming corporate role which always wanted more and more from him and although I work hard when I'm at work, I'm already giving up 37.5 hours of my life a week until I'm 68 (if not more) - I'll give extra time here and there when there's an urgent need to get something done but I'm just not willing to give up my time for free on a regular basis.
Am I being unreasonable??