The number of times a case can be reloaded depends on 2 things:
1) how hot your loads are
2) how much your sizing dies squeezes the case neck.
If your loads are hot, the primer pockets can get too loose to hold a new primer. Once that happens its time to trash the brass.
If your dies squeeze the neck down too much, the brass will work harden and crack after a few reloadings. You'll know when you reach that point when the neck splits down the side or breaks off completely. Work hardening can be delayed by annealing the necks with a propane torch until they barely turn dull red in a darkened room and then dropping them in a bucket of cold water. Anneal every 2 or 3 reloadings.
Just curious, why are you forming Win 284 when 7.5x54 brass is available from Graf & Sons?