I'm pretty new like you and last night I peaked at well over 400 with the rollers. A previous poster was dead on when they said the rules are relaxed when you are keeping a solid flow. The whole time I was hammering it, I never once saw the followup trainer around. My supervisor must have told him to take a walk while I was putting up boxes. You're right, bags always behind the walls, and get rid of them quick instead of saving them till the end. Someone said that's a bad habit to put them behind your wall but it is really the most efficient way. Don't get too caught up with making the so called "Perfect 10" wall. Sometimes you have to make due with what you're served down the belt. Also don't worry so much about getting it high and tight. Leave some space at the top to toss up bags and smalls into the gap. Some of the smalls are quite aerodynamic. I've had some of my best placements when they rebound off the top of the trailer. Hand to surface lasted about 2 nights for me. 200 or so per hour just isn't going to cut it when you're trying to get your numbers up. So far nothing but rollers for me but some extendo guys are insane here. I've heard of a guy who can throw up between 700 and 900 per hour with them. So keep going next next next and don't worry about fishing for the perfect package that will fill that gap just right. If you're messing with a box more than a couple seconds, it's wasted time.
-k