I'm studying Astronomy, so I've never had much time to draw comics :T on my first year of college I tried to draw comics whenever "I had the time" or "whenever I was inspired", which proved to be a disaster because I ended up not drawing a thing 
Now I take some time to work on my comic every Saturday, which works pretty well unless I have any other plan for Saturday (a family meeting, a convention, etc), then I'm screwed xD I try my best to keep working on my comic every week, it's almost like a job to me and I feel really bad when I can't update (right now I've had trouble finding the time to draw because I'm swamped with tests and work ugh....)