I'd rather have 30 incredibly intense and productive hours than 60 completely chill no stress do a little of this a little of that hours.

My old job was 60-70 hours of incredibly intense productivity (was working for a Japanese corporation) and I learnt at a rate well above what other workers would due to the intensity, but then I had a breakdown from burn out. Keeping that tempo for fewer hours is the best of both worlds. Employers need to be focused on output rather than time logged.