That implies that you have a fixed time for lunch and also chat during lunch. I may be the minority but I prefer to eat when I'm hungry and focus on the food instead of chatting. And there is also allergies, as a celiac, I have big troubles eating together with others - they may accidently contaminate my food

This is a very good question. I also struggle to find a good solution to process various signals (papers, tecniques, etc.) with my co-workers while maintaining proper work-life balance. Either you have to be a full time geek, or be left behind..