Do it till its tight.. just go from end to end like you do with lug nuts. No mechanic actually follows that stuff if there even is one.
If you're putting gasket maker on, put it on the cover, let it sit for a minute then put it on the diff, just put it tight enough for the gasket to come out the sides just a bit then stop and let it sit then tighten it down until snug after it sits for 5 minutes or so.
then fill and away you go.
Source: I've done it probably 50 times by now.