On the face of it the buff encourages people to simply play through the game without cherry-picking. However I still think that's probably sub-optimal.
Inferno item farming will be all about killing random boss packs and champion packs that have random affixes. I wrote about D3 end game farming here and about boss affixes here.
Not all boss mods are equal. Moreover, not all boss mods have the same impact on different types of character/build. A Barbarian for example isn't really hurt by the Vortex mod. The boss pulls the Barb in close, the Barb smacks him in the face, what's not to like? Nor is he hurt much by the Teleporter mod. The boss Teleports to the Barb, the Barb smacks him in the face, again what's not to like?
However Plagued (extra poison damage plus aoe poison damage if close), Molten (extra fire damage plus aoe fire damage if close), Frozen (extra cold damage, slows movement and attacks) and Electrified (extra lightning damage, spits out highly damaging bolts in its vicinity) - that would be a horrible boss to melee.
So it makes sense in that example for the Barb to skip very melee-unfriendly combinations and cherry-pick easy kills.
Also you only need to achieve a minimum boss kill per unit of time that will be determined by the developers before release. They're toying with the 15 minutes to an hour range. I don't think it will be 15 minutes. 15 minutes to find your next boss pack and kill them? In a game where people wipe for an hour on boss packs? It's too fast. They have to allow for people needing to afk and people with no faster run so I think it will be at least 30 minutes, possibly an hour.
If you have an hour to kill your next pack then it will certainly be possible to skip difficult ones. In fact if you spend an hour wiping you've lost your buff anyway.
Next they've said the buff will have a stacks cap of a "number you can count on one hand". There's lots of boss packs and champion packs in a game. There are a lot more than 5 just in the Beta content and that's just a part of one of the 4 acts. So there's lots of bosses to choose from.
The waypoint system will, I think, become part of a complicated routeway of boss running.
Teleport to Old Ruins
- run back to the Dank Cellar, check for a boss
Teleport to the Cemetery of the Forsaken
- run back to the Weeping Hollow, check for packs and shrines
Town Portal from the far end of the Hollow
Teleport to the Cemetery of the Forsaken again
check graveyard and each Tomb, skipping the jar of souls event (because it doesn't spawn a boss) but doing the Lady event (it always spawns a boss)
and then on to the Cathedral etc.
Possibly you might know how many packs normally spawn on each dungeon level so if Cathedral 2 only shows you one pack before you find the way down you might double back to check the other bosses.
It could be possible that once you have a full stack of Nephalem Valour an act boss drops better than random bosses so you might do 5 bosses + Diablo, save and exit, repeat over and over. But I think that's possibly less likely because for several of those bosses you'd be at gimped Nephalem Valour.
What might be better if Neph Valour makes Act bosses really good is you get your full set of stacks then kill each Act boss, Baal running style. So basically you'd kill 5 champ packs in the Cemetery or wherever then use the last waypoint in each Act to get the act boss.
Now there's an advantage to working through the quests - you get extra bosses on the quests. For example Manglemaw is a boss that only spawns if you're doing A Shattered Crown quest. Otherwise his spot is empty. So part of this optimisation process may include doing the quest.
|No quest? No shinies.|
However, even with all the waypoints and optimising the hell out of the system you may end up doing something very similar to playing through the whole game in the right order (with some boss skipping). So well done Bllizzard! Looks like mission accomplished.