I write code and debug for a living and often work similarly. I even force myself to take a break every hour, deep concentration or not. Necessity makes amazing

I write code and debug for a living and often work similarly. I even force myself to take a break every hour, deep concentration or not. Necessity makes amazing things happen. I definitely do not do more than 8 hour sessions, ever, and never without multiple breaks anymore. It works out fine, a little slower than before but that's mainly due to lack of communication and has nothing to do with hours worked.