with steel parts, as long as everything is aligned properly there is no break in; there's only wear. even the really really cheap hubs on entry level mountain bikes are good for thousands of miles as long as they're greased and adjusted properly. the rim/ spokes are almost always the weak point on the cheaper bikes. if the hubs are adjusted tight, they wear faster and begin to feel "broken in" after only 100 miles or so. if you adjust the hub properly, the cups and cones might take 1000 miles to get to the same level of wear as the "broken in" hub that has worn prematurely.
think of it this way: if a bearing is bigger than the rest, or there's a high or low spot in a cup or cone, the problem is GOING to normalize itself over the life of the hub NO MATTER how you adjust it. you can make it happen really quickly by adjusting the hub tight, or you can drag the process out over a lot longer time by adjusting the hub properly. in the end, it's a bicycle wheel, and any tolerance issues are so slight that it really makes no sense to cause extra wear and more friction by running a hub tight.
if you're really anal about it, just buy grade 10 bearings, adjust your hubs properly, and fuhgeddaboudit.