I have a limited tolerance for working long hours in the office. No matter how absorbing my work is, after about 8 hours of writing/analyzing, my brain is full. Also, the lights/computer screen tend to set off my migraines.
I can go a lot longer in the field. Most of the time I’m in the field, I have a million things to do or keep an eye on, and time passes a lot quicker, even when the environment itself isn’t terrific. Also, if I’m travelling for work, I don’t have much to look forward to back at the hotel room. So I might as well work longer hours and get paid for them.
However, there is a limit to the number of hours I like to work. After a long day, I need a long hot (if it’s cold out) or lukewarm (if it’s hot out) shower, time to eat a reasonable, non fast-food dinner, and a minimum of 8 hours to sleep. And a half hour to get dressed and eat breakfast in the morning. If fieldwork starts to eat into that time, I’m not a happy camper. Practically speaking, it means that more than 12 hours/day is pushing it. I can go up to 13, but I’ll get cranky/stressed after a week or so. So 11-12 hours/day, or somewhere around 60 hours a week, is what I shoot for (assuming a minimal commute to the field site).
The maximum number of hours/day I’ve worked is 15.5. In that case, the day went something like this:
7am: Start work.
1pm: Someone does a lunch run to the nearest sub shop. Eat when you can.
8 pm: Everyone is ravenous and threatening mutiny. Order pizza.
9 pm: Scarf down pizza, go back to whatever you were working on.
11 pm: Fall into bed.
If I am in charge of a (non emergency response) field project, there is no way I will let things get so bad that the field folks would have to work more than 14 hours a day for two or more days in a row. I would pull more bodies into the field (you can always scrounge up managers, newbies, or beg people from other projects), I would get an extension from the client, I would PLAN THE WORK BETTER at the outset. If you have people working in the dark, outside, around heavy equipment, and with no chance to eat properly or sleep, you have created an unacceptably hazardous working environment.