How do people work 80 hours consistently?

Last week I worked all 7 days out of the office including an 18 hour work day, and yet could only manage 76 hours.

How do people work 80 hours in a week? I don’t think a sane mind can do it…

Matlab you can spend 80 hours in the office, but shilling out productive hours looks impossible

And when you add travel + food breaks- The math breaks

For someone who’s done it consistently, can you point our how you did it?

Regards Daringly Yours