My longest shift was 21h, as far as I remember (8h was the normal shift, 1h of lunch break and 12h of overtime - including overnight).

However, several years I had periods of 3-4 consecutive months when I was working from Monday to Friday between 9AM-10PM and each weekend 8h/day.

So far, in ~13.5 years at the same company I achieved 5261h of overtime which, in normal time (~170 working hours per month) mean 30.94 months extra -- almost 2 years and 7 months of overtime.

I can't believe it sometimes...

- Edit: oh, and I forgot to mention - these were only the paid hours, those officialy counted. Besides them I have spent other hundreds of hours of overtime from dedication .