I was trying to stat an NPC who was trying to found her own hedge tradition via a combination of her own existing Supernatural abilities and integration of other hedge (/Hermetic...) traditions, and a lack of Magic Theory makes integration hard. Once he has the skeleton Magic Theory (and is improving it with the aid of the other Founders), life gets easier, but there's a period before that when he's just working off magical texts he's acquired and trying to synthesis something.
You need to roll Int + MT + 3 (Inventive Genius) + Insight Modifiers vs EF 18 to successfully generate an Insight.
So with Int +5, no Magic Theory (because you haven't invented it yet) and Inventive Genius, you have 8 + Insight Modifiers + die vs EF 18.
With no Insight Modifiers, you need to roll 10+ on a stress die, i.e. just under a 7% chance per season spent in study.
Mythic Intelligence (brilliant insight) will mean you only need 9+, and thus take you to about 17% - still not brilliant, but noticably better. That requires your character to have access to Heroic Virtues - Gifted people can't be Mythic Companions, so that means either Mythic Blood or Legacy.
If you do go down the Mythic Blood route, then at a stretch you could say that the accompanying Personal Power gave a bonus to Insight rolls - something along the lines of "Single-mindedness of the Concentrating Wizard" (ReMe 25, A&A p34), which gives a +3 bonus to Concentration rolls at the expense of failing any other Intelligence roll for the duration of the spell. But for Insight rolls, obviously.
The alternative approach is getting good bonuses from the sources of Insight you're studying. Bonisagus appears to have been working off a combination of Mercurian rituals he'd learned, and a large eclectic collection of texts. Ancient Magic doesn't actually give much guidance on the bonuses different sources of Insight can give, but Hyperborean Magic has insight sources that range between -3 and +4 (mostly +-2).
Hedge Magic specifies that Gifted teachers can add their Int + (Hedge Magic Theory) to the Insight roll by acting as a lab assistant to the researcher. I don't think it's ever explicitly specified whether the Cult of Mercury had it's own Magic Theory, but given the standalone nature of its rituals and the fact that Bonisagus felt the need to create a theory from scratch I'm assuming not.
So some sort of virtue that gave you a bonus to acquiring insight from Insight sources would be good, but I don't think there are any examples in canon.