There's ~151.9 working hours in a month if you go by the 35 hours per week the French (e.g. Portha) usually work. Three volunteers and you've got a full time employee at that rate. What you're saying here is that meeting a part time job's expectations, on top of working a full time job, whether that's being a student or working professionally, isn't really that much. I spend around the same amount of time doing extra outside of my job, and I get greater than $1000 worth of value out of that time per month.