I've seen it done two directions but only on turf that has a healthy root system. It does make a great difference to do it more than once. Concerning the grooves, we basically topdressed them out last year. This year we have roller

I intend to bury them in sand again and then put the roller on to help smooth things out. We were putting in the high 9's with very little affect on the ball in 1 week after a single verticut and the aerification.