Comment by ashr

I don't believe 2.5 hours is representative, so please cite these studies. Personally,senior engineers (individual contributors) that I have worked with spend 4-6 hours per day making significant contributions on their own and the other 4-2 hours working/coordinating with their team and sister teams. The only plausible scenario where one can do an acceptable job in 2.5 hours per day is where a senior person is doing the job of an entry level person. For people managers, having effective 2-4 hour days on an ongoing basis are very unlikely in my experience. I am open to be surprised with examples that prove otherwise.