The most hours I worked in a row - more or less, going by the definition of having no time to enjoy any personal activities aside from sleeping - were about ~17h.

I specifically remember this event because of the amount of hours of pointless work that generally went into that project and there was this one time when we - not only me as a technician, but also most of the engineers - had to build hundreds of complex devices in-house to meet an important customer's deadline because we had problems with a subcontractor at that time.

We did it in time, there was pizza afterwards as well as some questionable sense of achievement, so apart from a wasted weekend and sore muscles in my hands for the next days I didn't regret it all that much. So yay, I guess.