While most of what you say is good, your final bit of advice is wierd:
That is not optimal for two points of Virtues. For example, let's look at the combined score of 36 again. With your suggestion:
Te 12, F1 12, F2 12 -> 36 for a cost of 78+52+52=182
Now try it with Affinity + Puissant in the Technique:
Te 13+3, F1 10, F2 10 -> 36 for a cost of 61+55+55=171
Attaching two points of Virtues to the singleton is more effective than attaching one to each of the pair. Sure, if you compare Affinity in the singleton to Affinities in each of the pair, the latter is better. But the same number of Virtues have not been spent and this is why the latter is better.
Additionally, there is another point there to be adjusted. We remember we are restricted to two Affinities. You might argue this is the point of putting them in the pair. But why an Affinity in each of the pair? Why not one in the singleton and one in the pair? If you keep everything balanced, this clearly saves just as much as putting them in the pair. But now you don't have to keep things balanced, being able to go for a slight imbalance as I've been showing is more optimal. Here is something more optimal with two Affinities, this time putting one in the singleton and one in one of the pair:
Te 14, F1 11, F2 11 -> 36 for a cost of 70+44+66=180
Note that this has saved two experience over your suggestion of putting them in each of the pair.
Here are the best options between Affinity and Puissant (assuming high enough levels that Affinity > Puissant and assuming weakened Puissant of only +50%) for TeFo(Fo) or Te(Te)Fo with Focus:
1 Virtue: Affinity in the singleton
2 Virtues: Affinity + Puissant in the singleton (what several of us suggested above)
3 Virtues: spread out two Affinities and one Puissant, one to each Art
4 Virtues: Affinity + Puissant in the singleton, Affinity in one of the pair, Puissant in the other of the pair
But remember that these Affinities and Puissants are not as strong as generally due to the distribution of experience, while general experience bonuses can be more effective. So you may well be better off putting points into things like Book Learner. Also, advancing three Arts is slower, so it takes longer for Affinity or Puissant to become better than something like Skilled Parens than it might otherwise.