If I can afford to use something else and it will do, I'll do that. If I'm drowning in an aspect I rarely use, I don't use that aspect. I make better aspects with it.
And the thing that you seem to be forgetting @
Iluvalar is that one rarely has only two aspects to link. If one has to combine, say, 5 aspects, one MUST make every aspect choice the best fit, because the grid is a fixed size, but your aspects are not limited. If I can afford to use my million metallum instead of a more rare aspect, I do. But I don't just take into account how much I have, in fact, I don't. I take into account what fits the puzzle best. And like I said, Praecantio is a great aspect, not because it connects to a lot of things, but because few things allow for such a short bridge between aspect chains as it does.
Hence why I was always pissed when ThatOneSlowking said one has no use for Ignis, because if one has no use for Ignis, they are done all their research now.