Ok here how i count the max models total :
I'll take Schlaf 3-50 points lists as an example (since i don't own twice the same model, my lists aren't suited well for explaining, courtesy of schalf of course even if i didn't ask ^^) :
High Executioner Servath Reznik (*6pts)
* Castigator (8pts)
* Crusader (6pts)
* Scourge of Heresy (9pts)
Choir of Menoth (Leader and 3 Grunts) (2pts)
Daughters of the Flame (Leader and 5 Grunts) (5pts)
Exemplar Cinerators (Leader and 4 Grunts) (8pts)
Exemplar Vengers (Leader and 2 Grunts) (7pts)
Holy Zealots (Leader and 9 Grunts) (6pts)
Knight Exemplar Seneschal (3pts)
Reclaimer (2pts)
In this first list i list 34 models.
Grand Scrutator Severius (*6pts)
* Redeemer (6pts)
* Revenger (6pts)
* Vanquisher (8pts)
Choir of Menoth (Leader and 3 Grunts) (2pts)
Deliverer Sunburst Crew (Leader and 2 Grunts) (3pts)
Exemplar Cinerators (Leader and 4 Grunts) (8pts)
Exemplar Errants (Leader and 5 Grunts) (5pts)
Flameguard Cleansers (Leader and 5 Grunts) (5pts)
* Flameguard Cleanser Officer (2pts)
Knights Exemplar (Leader and 5 Grunts) (5pts)
Reclaimer (2pts)
The Wrack (3 wracks) (1pts)
Vassal Mechanik (1pts)
Vassal of Menoth (2pts)
In the second list, there is 31 new models, we don't count the ones that were in the previous list (Choir, cinerators, reclaimer) so the total for the two lists is 65.
Vice Scrutator Vindictus (*6pts)
* Vigilant (4pts)
* Crusader (6pts)
* Templar (8pts)
Choir of Menoth (Leader and 3 Grunts) (2pts)
Choir of Menoth (Leader and 3 Grunts) (2pts)
Deliverers (Leader and 5 Grunts) (5pts)
Exemplar Cinerators (Leader and 4 Grunts) (8pts)
Holy Zealots (Leader and 9 Grunts) (6pts)
* Holy Zealot Monolith Bearer (2pts)
Knights Exemplar (Leader and 5 Grunts) (5pts)
High Paladin Dartan Vilmon (3pts)
Reclaimer (2pts)
Vassal Mechanik (1pts)
Vassal of Menoth (2pts)
In this last list, here's how it becomes tricky, new models are Vindictus, vigilant, templar, the second unit of choir because it means that schlaf will bring a second unit of these guys that will be on the table with the first one, deliverers, the monolith bearer (but not the unit of zealots which already appeared in list 1, if you have a 6 models unit which becomes a 10 models unit in another list, don't forget to count the 4 new guys) and Vilmon.
So that there is 15 new models which brings the amount of models to 80 models (i hope i didn't make any maths mistakes...)
I hope you'll get the idea ! You can do this on your 6 lists and chaeck taht your total is ok. But remember that you made it, and don't forget to show your pride the 26, 27th !