This is my first post (not reply) which was inspired by a UK hc run I were in recently where a person complained about it being too long for only 3 bosses. I have made a list of how many packs there are between each boss in each instance, this is packs and not pulls as I know there are some people who grab all the mobs in rapid succession, literally without dropping combat.
Order is normal level difficulty.
Incoming wall of text. :-\
Utgarde Keep:
Not counting patrols of less than 2 mobs and only taking the left side of the drake room - not including the first proto.
8 Packs before Prince Keleseth.
9 Packs before Skarvald & Dalronn.
4(5) Packs before Ingvar.
Grand Total: 21(22) Packs of mobs between your entry and the last Boss. (7 packs per emblem/4.2 if random)
The Nexus:
Still not counting patrols of less than 2 mobs, will however count the single drake at the start and the one in the boss room.
4 Packs before Commander Stoutbeard/Kolurg.
5 Packs before Grand Magus Telestra.
5 Packs before Anomalus.
8 Packs before Ormorok the Tree-Shaper.
2 Packs before Keristrasza.
Grand Total: 24 Packs of mobs between your entry and the last Boss. (4.8 packs per emblem/3.43 if random)
Azjol-Nerub:
Not using the skipping tactic for Hadronox, counting in the 3 minibosses.
5 Packs before Krik'thir the Gatewatcher.
3 Packs before Hadronox.
1 Pack before Anub'arak.
Grand total: 9 Packs of mobs between your entry and the last Boss. (3 packs per emblem/1.8 if random)
Ahn'kahet: The Old Kingdom:
Still not counting patrols of less than 2 mobs, skipping what I can.
5 Packs before Elder Nadox.
8 Packs before Prince Taldaram.
3 Packs before Amanitar.
4 Packs before Jedoga Shadowseeker.
3 Packs before Herald Volazj.
Grand Total: 23 Packs of mobs between your entry and the last Boss. (4.6 packs per emblem/3.29 if random)
Drak'tharon Keep:
Still not counting patrols of less than 2 mobs, Raptors on Dred counts as 1 pack, skipping what I can.
7 Packs before Trollgore.
2 Packs before Novos the Summoner.
4 Packs before King Dred.
5 Packs before The Prophet Tharon'ja.
Grand Total: 18 Packs of mobs between your entry and the last Boss. (4.5 packs per emblem/3 if random)
Violet Hold:
This one is easy, lol.
5 Packs before Random Boss.
5 Packs before Random Boss.
5 Packs before Cyanigosa.
Grand Total: 15 Packs of mobs between your entry and the last Boss. (5 packs per emblem/3 if random)
Gundrak:
Counting all the elementals in the Colossus room as 1 pack, not skipping through the water untill after Colossus, 3 Gorlocs is 1 pack.
3 Packs before Slad'ran.
6 Packs before Drakkari Colossus/Elemental.
2 Packs before Moorabi.
3 Packs before Eck the Ferocious.
4 Packs before Gal'darah.
Grand Total: 18 Packs of mobs between your entry and the last Boss. (3.6 packs per emblem/2.57 if random)
Halls of Stone:
Counting the big stone dudes as one pack, pulling 2 of the mechanicals when possible.
16 Packs before Krystallus.
5 Packs before Maiden of Grief.
5 Packs before Tribunal of Ages.
2 Packs before Sjonnir the Ironshaper.
Grand Total: 28 Packs of mobs between your entry and the last Boss. (7 packs per emblem/4.67 if random)
Halls of Lightning:
Still not counting patrols of less than 2 mobs, Slag room is 1 pack, skipping as much as sensible and going to the right upon entry and after Ionar.
4 Packs before General Bjarngrim.
6 Packs before Volkhan.
5 Packs before Ionar.
6 Packs before Loken.
Grand Total: 21 Packs of mobs between your entry and the last Boss. (5.25 packs per emblem/3.5 if random)
Caverns of Time: The Culling of Stratholm:
Counting the gauntlet at last as 4 packs.
4 Packs before Meathook.
4 Packs before Salramm the Fleshcrafter.
4 Packs before Chrono-Lord Epoch.
4 Packs before Infinite Corruptor.
0 Packs before Mal'ganis.
Grand Total: 16 Packs of mobs between your entry and the last Boss. (3.2 packs per emblem/2.29 if random)
The Oculus:
Only counting ground-based packs, not counting patrols of less than 2 mobs.
5 Packs before Drakos the Interrogator.
6 Packs before Varos Cloudstrider.
3 Packs before Mage-Lord Urom.
0 Packs before Ley-Guardian Eregos.
Grand Total: 14 Packs of mobs between your entry and the last Boss. (3.5 packs per emblem/1.75 if random)
Utgarde Pinnacle:
Still not counting patrols of less than 2 mobs.
6 Packs before Svala Sorrowgrave.
4 Packs before Gortok Palehoof.
0 Packs before Skadi the Ruthless. (The mobs are part of the encounter)
7 Packs before King Ymiron.
Grand Total: 17 Packs of mobs between your entry and the last boss. (4.25 packs per emblem/2.83 if random)
Trial of the Champion:
Counting the champions and their adds as one pack.
3 Packs before Grand Champions.
3 Packs before Eadric the Pure/Argent Confessor Paletress.
0 Packs before The Black Knight.
Grand Total: 6 Packs of mobs between your entry and the last Boss. (2 packs per emblem/1.2 if random)
Forge of Souls:
Skipping what I can, counting the ghosts at last as one pack each.
8 Packs before Bronjahm.
3 Packs before Devourer of Souls.
Grand Total: 11 Packs of mobs between your entry and the last Boss. (5.5 packs per emblem/2.75 if random)
Pit of Saron:
Skipping what is possible (Not jumping into the water in the middle/not skipping the 2 first ramp packs), each big skeleton counts as one pack, so does the shamblers before Ick.
5 Packs before Forgemaster Garfrost.
6 Packs before Ick.
5 Packs before Scourgelord Tyrannus.
Grand Total: 16 Packs of mobs between your entry and the last Boss. (5.33 packs per emblem/3.2 if random)
Halls of Reflection:
Skeleton Commander is 1 pack.
4 Packs before Falric.
4 Packs before Marwyn.
5 Packs before being saved.
Grand Total: 13 Packs of mobs between your entry and the last Boss. (4.33 packs per emblem/2.6 if random)
Hope you enjoyed this as much as I did making it (hopefully you enjoy it more).
tl;dr version:
UK: 7/4.2 PPE
Nex: 4.8/3.43 PPE
AN: 3/1.8 PPE
OK: 4.6/3.29 PPE
DtK: 4.5/3 PPE
VH: 5/3 PPE
Gun: 3.6/2.57 PPE
HoS: 7/4.67 PPE
HoL: 5.25/3.5 PPE
CoS: 3.2/2.29 PPE
Ocu: 3.5/1.75 PPE
UP: 4.25/2.83 PPE
ToC: 2/1.2 PPE
FoS: 5.5/2.75 PPE
PoS: 5.33/3.2 PPE
Hor: 4.33/2.6 PPE