This is totally a personal thing, so from my point of view.
I am studying a course of 120 credits level. last year I studied a 30 credit, the same this year and a 60 credit unit the next, all in all this means I am taking level one over 3 years, and in the end it will take me 7 years to complete my degree.
I am taking this route because, I work full time often >50 hours per week, and I also have a young family who I actually want to see now and then.