I usually work during evenings/nights, but I'll work intermittently through the entire day when given the chance. If I want to produce while at school, I'll probably have to switch to mornings. I'll switch between songs occasionally to keep from burning out within the DAW. I also like to get high/(rarely) drunk and produce, but only if there's a song in progress. Otherwise, I don't get anything done. Luckily, I produce while sober 98% of the time lol I can work for hours on end or get distracted every now and then, depends on my attention span at the time. Sometimes I let myself listen to previous songs to get myself pumped for the next/current one. I like hearing my progression, even when its subtle.

I need to have at least 3 hours of free time, and if I don't, I don't and can't produce.
I like to focus on one song at a time because it helps me stay focused on the original theme/feel of the track. It's also because I'm impatient, the ideas that make it into a song are ideas that I really like and I want to finish it ASAP.