As the title says, has the code of hermes (as written) gotten in the way of your games in a negative way? Which part?
Has anyone changed/House Ruled the basic Code of Hermes for their game before starting a Saga?
In a 700's game I ran, the PC's helped change some of the basic tenants of it. They added an option that non hermetic wizards could join, die... or be enslaved. (They were dicks, but that made it fun.)
I've seen over the years the clause "Nor will I interfere with the affairs of mundanes and thereby bring ruin upon my sodalis" cause a lot of issues. Prior to 5th, this meant Wizards had to hide away. 5th edition really tried to change that (and I commend the line for that) but the original clause was still there.
Making your peripheral code - and its interpretation of the Code of Hermes - fit the needs of your area is typically the reason, why new Tribunals are founded (like the Novgorod Tribunal after the Schism war) or planned (like the Lotharingian one in 1220).
Which other game? There are a few! (oMage? oVampire?)
Another issue I've seen (in the forums here) is that apprentices MUST have 15 years of instruction. There's nothing explicitly saying that that is mandatory. (Edit! The Sundered Eagle has a canonical peripheral code ruling saying Apprenticeship must take 14 years. Other books do not, so far as I can recall.) The various HoH books have some detail on what gauntlets look like, but beyond that? Why not have an apprentice done in 5 years? They can easily have Latin 4, Magic Theory 3, Artes Liberales 1, Scribe 1, and can cast a few level 10 spells. There are social implications for graduating such a "magus", yes. But it's not illegal to do that, barring peripheral code rulings.
As a point in favor, the peripheral code in Thebes actually requires a 14-year teaching cycle. Any apprentices are acquired ONLY at tribunal from the available pool, they're given a check-in testing at the next tribunal, and presented for gauntleting at the tribunal after that. They are often given training in Artes and Greek (maybe Latin) a year or three before that.
That expression tends to be a reference to a specific, widely known game, named for giant fire breathing lizards and restrictive underground enviroments, sometimes used to contain prisoners.
You have - of course - read both The Founder's End (HoH: TL, p. 8) and the notes of the Code of Hermes in the Guernicus chapter of the same book (HoH:TL, p. 52-53)?
If it was purely for the skills, I've seen covenants so organized that apprentices had those skills before their Arts were opened, but so what?
They have the right to 15 years of apprenticeship.
HoH:TL doesn't say an apprentice has to have 15 years of apprenticeship. Both core and HoH:TL state the magus must teach them at least one season per year, and that is an entitlement of an apprentice. After 15 years, the magus is expected to test them, and it's a low crime to maintain them for longer then that (barring some exceptions, of course).
Bonisagus's story does make for an apocryphal story. It is not law.
...which is the first sentence of the apprenticeship section of the character design chapter.
It doesn't say that that's carved in stone in the list of the Ars Magica commandments, but I think it's clear enough to cover pretty much all cases (also on that chapter there isn't also any reference to the childhood's 5 years to be mandatory). Of course then there can be issues, like Tytali slaying their parents and thus being considered gauntled and welcomed by the rest of the house, or magi dying while being parens, or Tormenting Parens that think character's apprenticeship isn't over, or whatever.
IMS if anyone comes with a character design claiming that their apprenticheship lasted anything different to 15 years I would just require the 15 years XPs and spell levels to be spent as in the character creation rules, and then just add whatever they say to justify that as character background story. You are a Tytalus that killed his master at age of 13, after 3 years of training? Cool! Then show me you picked the Poor Parens flaw, that you have a cool reputation in the house and mechanically just consider that your apprenticeship lasted 15 years anyway, with you spending most of the time learning stuff on your own, replacing seasons working for your master with seasons spent servicing other magi to gain access to their teachings or their library.
Besides that I think the 15 years rule will probably be in each Tribunal's Pheriferical Codes. It balances the service magi can expect from apprentiches, ensures them 15 seasons of study and more important gives the order 15 years to decide if that young punk deserves to be taught Parma or to be burnt down on the spot.