If it's a sealed bearing, don't use grease zerks.
If it's not a sealed bearing (meaning there are separate seals you buy that aren't attached to the bearing itself), then use grease zerks.
Great thing about grease zerks is that you can pressure up a degreaser in there and clean out the bearings, then fill it back up with grease.
Bearing maintenance without disassembly!  Just causes a bit of a mess LOL
Still a good idea to disassemble at regular intervals to inspect the bearings and make sure they're still in good shape, no rust or damage, etc.