I've had to work 15-18 hours days to get things done lately, the various elements of my role meaning I have to find time for work in the field and then doing administrative type duties; it's really quite diverse and, of course, I don't want to say too much here. The causality (lately and often) is sleep - I don't always get a lot in one session. It's all good though, I make it work, like you do, and days like today don't seem as hectic due to the environment I'm in.
My weekends are usually used in the same way yours are, but sometimes I've got to make a call on it and go in a different direction.
I used to have long days like that, but now that I have another person on staff it isn't too bad. We keep up on things quite well. Weekends are interesting. Usually we are running around watching our nieces and nephews play sports. Right now I am here replying to you, and my wife is next to me on the couch working.
I don't mind the long hours when they present themselves...as long as they're balanced out. It's when they are not that things tend to get out of control.