On normal 16 man at least you put all 16 people at one pylon. Start the puzzle and kill all the enemies spawn ( Should be roughly 5 x 3 spawns 1 x insect, 3 x 3 spawns, 1 x insect, 1 x 3 spawn, 2 insects) After the final 2 Insect Mobs spawn no more enemies will spawn at that pylon.
At that point move the raid ( minus perhaps one or two if you want to continue to solve the puzzle as you fight on the other side to save time). repeat the process on the second side and solve the puzzle. Then collect loot.
If you leave 2 members at the first pylon you can solve the entire puzzle well before the last spawn on the second pylon which saves time/fighting.
Ahh, now that makes sense. We thought of that but someone said that if you waited to clear all the adds at the first pylon, the puzzle would lock and you'd be boned. Bad information I guess.