hours out of class?

This week's problem-set is hard. Gauss' law problems see to fall in two categories: trivial exercises with standard geometries (line, sphere, sheet), or very hard problems with complex setups, e.g. uniformly charged sphere with a hole in it which you replace with two spheres, one the original size but now complete, and a small sphere the size of the hole but with opposite charge.

I have also received students' concerns about the amount of work. I use the guideline of 2-3 hours of work outside of class meeting times, so that is 10-15 hours of work for the 5-credit course. I wonder how many other courses follow this guideline and has the student expectation of load decreased.