Abridge the parts the troupe isn't interested in.
tl;dr Play the parts you like, crunch the numbers without storytelling the rest.
Use a set interval in between the adventures of the magi.
Base advancement
Sort out an amount of vis, xp, and seasons allotted between the interesting bits of story telling. Each player's magus gets this in addition to whatever they found in their adventure. Additionally, permit long projects to be put down and picked back up.
This avoids trying to refactor a rather complex system to fit shorter time scales and different resource constraints.
Account for time, but don't play through it.
From the player troupe's point of view, the time on the wall clock between the parts of the story they want to play is the import bit. The amount of story time between those events isn't felt by the players if you just skip it.
This simplifies the issue of passing time. We did this for a couple of one shots when playing through some adventures to get used to the combat & casting system using 8 season intervals. Basically, a bunch of magi go adventure every other year. Its enough xp and time to make a new spell, improve some skills, or improve an existing skill. It felt a lot like leveling up.
Grogs or companions are integral to many combats.
There are things in a saga that don't react well to bullets... arrows. Those are usually magi trying to cast a spell.
Grogs and companions provide the front line combat roles.
They soak hits and dish out mundane wounds.
Have a bunch of pre-generated thug, berserker, archer, and footmen grogs for the magi to take with them as hirelings. We found the example grogs from the core book sufficient.
Lost of Content and Style Warning
Eschewing the "troupe style play" laid out in the introduction of the Ars Magica Fifth Edition introduction has consequences.
No individual story lines.
With all the group magi present for every story even the group plays through, there's little opportunity for individual story lines.
Limited opportunities for player investment in each other's story lines.
We had a house rule that a player was never allowed to play their own companion. So the other players had interesting characters to perform an integral part of a scene that was involved with the present magus's story line.
In the rare cases when a player didn't have a magus or companion, they were solely responsible for the grogs, the grog peanut gallery comments, and assistant story guide decisions.
Lots of content doesn't work without companions.
The Gift is a heck of a nerf for dealing with mundane people. It most cases, it makes normal interaction impossible. It also makes dealing with clergy directly very dangerous. The setting is geared in such a way that the mundane, divine, and arcane are all dangerous and interesting realms to tread in.
Eschewing or removing companions and grogs limits the kinds of stories that the troupe can effectively engage in.
The Covenant is more than the Magi
There are more stories to be had than just the adventures and times of the magi. E.g. While the magi busy in their labs trying to concoct their piece of a plan that will save the entire Hermetic Order from an ancient Roman necromancer in league with demons, the hijinks of a few companions being sent to procure a rare animal that turns out has gotten loose at a festival in a fiefdom controlled by a rival noble.