Measure work done rather than hours worked. That’s what Francis Bacon warned us for in 1612. “Affected dispatch is one of the most dangerous things to business that can be… Therefore measure not dispatch by the times of sitting, but by the advancement of the business.”
Combining this visionary statement with Parkinson’s law from 1955, which claims: “The amount of work will always expand as to the amount of time available.” Meaning, if you have one year to complete your thesis, somehow it takes one year to complete. If you have six months to complete your thesis, magically, it takes but six months to wrap it up.
Spending more time working is only interesting if the output remains high. Favor output over time.