I don't know of this particular groundschool, but I think it would be irresponsible to think that you can just do a days study for each exam and be a confident and safe pilot afterwards.
There is so much information to learn; I would imagine this is more of a brush up class after you've studied to help you get through the exam, but I could be wrong.
I studied pretty hard for my PPL, and find myself reading and learning constantly since, and still have a lot more to learn.