If CAPS LOCK is turned on, Lightroom will automatically advance to the next photo when you flag or rate a photo. You don't have to tap the arrow to move on.
There, I just halved your keystroke workload for your initial pass at culling/rating
Yeah, fair enough but does rendeering the 1:1 previews at import not then make the catalog huge?
They can if you allow them to, or they won't if you tell Lightroom to not allow it to: