I've played with as much as 20+ yearly pawns of vis/magus, and as little as -4 (meaning: every magus had to obtain 1 pawn/season and "pay it" to an external entity, or face dire consequences). Currently, the magi in my saga are mature and fairly powerful, and they net about a dozen pawns each, perhaps a little more, with ample stocks. I am not counting vis earmarked for covenant's use" (e.g. casting the Aegis).
From my experience, there are roughly 4 levels of yearly vis income, in terms of the reactions they elicit in our PCs.
Starving: 3 pawns/magus or less. At this level, getting more vis is a high priority for most covenants. Our magi still won't spend seasons to acquire it (they are almost invariably jealous of their time). But they will be willing to spend a few days every season to chase it, will constantly be pushing their mundane servants to look for it, and will often sacrifice lesser goals/advantages for it (e.g. they will be willing to antagonize other covenants/supernatural creatures over it). Vis is virtually never spent in certamen, to boost spellcasting, or to heal a grog, and is certainly never given away; it's valued more than confidence.
Hungry: 4-7 pawns/magus. At this level, getting more vis is important, and the magi will still be proactively looking for it (and pushing their servants to do the same), but it's not their top priority, and they will rarely sacrifice magical/political resources for anything other than vast quantities of it. They will occasionally spend it in certamen and the like if the stakes are high enough. 1-3 pawns of vis are "valued" about as much as point of confidence. I think this is the sweet spot for sagas involving young magi.
Sated: 8-15 pawns/magus. At this level, magi don't casually throw away vis, and welcome it when they obtain it. But they won't be proactive about obtaining more (unless the stocks are really really low), nor will they sacrifice magical or political resources for it (even vast quantities of it). They will often spend it to boost certamen, and spellcasting, if somewhat conservatively. They will occasionally spend it to help valued grogs, or give it as a gift to a favoured redcap. It's definitely worth much less than confidence. This is the spot where our magi tend to end up when they "grow up".
Bloated: 16+ pawns/magus. At this level or higher, magi tend to be very casual with vis: they refrain from spending it more to avoid botches than anything else, but they will not hesitate to burn a rook for what is mostly show. It's almost impossible for vis not to accumulate in vast quantities over relatively little time. Paradoxically, I've found that vis shortages are more common at this level than at the previous one, because magi tend to lose track of how much they have!