The main reason for doing several smaller drainn/refills is to avoid any potential problem with an empty pool... heaving, cracking, etc. If you drain the pool, there is only the pressure of the ground pushing in on the walls, and no longer pressure from the water pushing back on the walls

ETA: keep it at shock levels until you have O CC, then let it drift back down to 8 or so, if you keep the high CYA