I've learned 3 each 3/4" is not enough if the wind is dead calm for me. My last 5 or so cooks that were overnight have been at 175* when I woke up. My smoke plume rose strait up for 20 feet. My last build had 3 each 1" openings.
UDS', mUDS, COS. Weber gasser & kettle. Thermapen,Digiq2, Golden-Tiger