Class 2 gets cut back immediately after blooming. General instructions are to wait until it's actively growing in spring, April to May, and remove any scraggly (dead looking) top growth then but I'm cutting it back to neaten up, not for maximum flowers.
There's also a class 2 that borders on 3 - Niobe being the most common one. With that you can cut half the stems to the ground and leave the rest. I'm sure many people have their own procedures for pruning that one.
Are you confused enough yet?
