The previous responses to your query have it right, in my view: there's no canonical answer, do what works best for your saga.
Having said that, my opinion is that high-powered sagas tend to lead to conclusions that have non-trivial implications about the game universe at large. One example is a conversation I participated in about apprentice training that moved on to the basic question of: how many +5 Com individuals are there in the world? This doesn't seem like it matters much, but because Com plays directly into the experience a teacher gives a student (and, more importantly for magi, the quality of books written), it can have pretty massive implications.
If you take the perspective that your saga's covenant is the luckiest/most heroic/whatever covenant in the area, and therefore ends up managing to get more vis/books/people/cool stuff than other covenants, your world balance isn't threatened, but political balance with other covenants may be. If word gets out, will other covenant's magi be trying to move in to your covenant, because you've got the best books, tutors, and most vis? Will they be ganging up to take your covenant down?
On the other hand, if you go power-heavy and assume that's normal for covenants in general, I think you tend to run into inconsistencies in the world, such as "why haven't all these hermetic breakthroughs already been made? It's so easy! And how can any faerie be a threat?" (Don't get me wrong; there are ways savvy storytellers can work around those issues.)
I find that the average Saga you hear about runs a bit power-heavy for my tastes. This is understandable, as many RPGs scratch people's wish-fulfillment itches, so they want characters who can be the best at something. If that's what your players want, than I'd definitely recommend trying to come up with a Saga concept that goes well with that.... something properly epic. But if you want something more gritty, aiming to make goodies more scarce would probably be advisable.
The challenges on the frontier tend to be more mythic and less political (compared to, say, Rome), you can probably afford to worry about player balance versus the order at large less. Perhaps have fun with a situation where your characters are the best at their specialties, perhaps that the order has ever seen... but nobody cares, because they're off pioneering outside of civilized society.