When I have a lot of hair spray in my hair, it becomes all tangled and very difficult to remove in the shower. I discovered that if I use hair conditioner on those areas before shampooing, the hair spray comes off more easily.
So I use conditioner first, then I shampoo and then I use conditioner again. This has been working for me. I try to avoid using hair spray too often though, because I don't like having to wash my hair for half an hour afterward.