It is possible though not generally recommended to experiment while opening your apprentices arts. Obviously a botch or deleterious side effect could destroy the youths gift, or hobble him for life. But what about all those other effects that on the results char aren't necessarily bad or are possibly really goodt how would you interpret them.
For instance there are the side effects. The arts are still opened exactly as advertised but there is some other effect attached to the opening that wasn't intended.
Minor or Major Side effects. (the ones that the effects are neither good or bad)
Minor or Major benefits.
Then there are the modified effects which get even weirder.
How is a gift openings potency increased.
What is the difference betwwen the modified effect chart results of 9-10 (modified effect) and the 11+ (completely changed effect) when it comes to an art opening.
Arts are supernatural abilities and not covered by experimentation in a Lab context , imho.
Hedge Magic, page 51, "The magus may instead use an Insight to vary his technique when Opening the Arts of an apprentice. A roll should be made on the Extraordinary Results table for Experimentation, as normal, and if a Discovery results, the Apprentice's Gift is Opened as normal and the magus earns 5 breakthrough points. Other results may damage the apprentice's Gift, causing him to acquire Hermetic Flaws or even lose his Gift."
Honestly I'm having difficulty imagining anything that couldn't be simulated with existing hermetic virtues and flaws. Since the only canon breakthrough this is possible for is subtle opening, maybe granting him an appropriate supernatural ability combined with a deficiency in an art could count as a side effect. Like, deficiency in Intellego, but he has the divining virtue(s) from Mysteries. He just does divination differently.
I´ve added V/F for this in the shape of "Minor Gift"(Variable V/F) which allows taking a few of either Te or Fo, fewer if taken as Arts, or by spending some extra Virtue points, up to getting all Arts as Abilities or a mix of some Te and some Fo as Arts. "Damaged Gift"(Minor Flaw without social penalty, Major Flaw with penalty) which disallows XP to all Arts for the character; the character can still do labwork normally, and can cast spells "normally" as long as they can get some kind of bonus(Puissant for an Art is enough(but only for spells using THAT Art), as is positive Cyclic Magic, Method Caster, Mastery, Lifeboost etc etc).
"Limited Gift"(eeh, i forgot how i did the mechanics for this one and i dont know where i have my notes right now... )
Mmm, interesting variant.
If you want a simple version, just add a Hermetic Minor/Major Virtue as the result.
Exaggerated sigil is one possibility at least.
A coupled setup of Cyclic Magic V/F(positive at night, negative in daytime for example) another.
A simple "generic" version could be to just give some extra XP only for Arts.