I usually use a normal debugger to find a problem when I can see its symptoms but not the original caus. That way I can break on the line that is causing the symptom, check what the variables are like and go back up the call stack to find the origin of the incorrect state. I can do all that in one shot (maybe a couple if I need to break somewhere else instead) rather than putting prints everywhere to try and work out what the call stack is, and a load of prints to list off all the local variables