A works/construction department in a medium-sized town. They had an Excel spreadsheet that had a HUGE number of screens. Anyone wanting to do commercial real-estate construction had to not only fill out these forms, but keep them uptodate and submit the updates at end of each work day.
The thing was HUGE and had lots of interdependent screens, where if you picked an item from a dropdown menu, it unlocked a bunch of other complicated screens or panels, and so forth. Each screen had 30-40 items and fields on it, and there were multiple dozens of screens you had to tab through.
To run it on the jobsite, construction contractors HAD to buy a pen and touchscreen Windows ‘tablet’ ($$$). The whole thing had been written and maintained by one guy over the course of a few years.
EVERYONE hated it. The guy who had written it wanted to get promoted to management, but nobody else wanted to maintain it so he was stuck.
72 hours to finish a design project for a client. Hard deadline to make it to the printers in time for a trade show. By the end, I couldn’t see straight. Slept for 18 hours after handing it in.
Saw the end product at the trade show. Horrified to pick out so many small errors. Customer was happy, though. Got two more projects.
Never did it again, but it was good to know I could.