This is not as grueling as it may seem. If you set up a Master League with automatic transfers etc, and sim all your matches (let the coach handle them rather than play them yourself), you can burn through a season in 30-40 minutes. I can confirm however, IT DOES HAVE TO BE 10 SEASONS WITH THE SAME TEAM (i.e the same Master League save file).
Here's a bit more of an in-depth guide:
Start a new Master League game. I recommend choosing a team from the Dutch Eredivisie, as the league only comprises of 18 teams not 20, making for 34 league games in a season, not 38. Their cup ties are also played over 1 leg, not 2, and resolved on the night rather than a replay. (You can edit the rules of some other leagues to be similar to this, but to be on the safe side, I just chose a Dutch team).
The next thing you need to do before you start is take a look at the General settings. I think you're safe to leave the Match Level on whatever you want. As far as I know, it only applies to games you play. Change the Match Time to 5 minutes though, incase you do need to play a game or two.
Most importantly, change the Negotiations setting to "Leave to Scout". This way you'll have a constant stream of new talent coming in, and older players going out, without you having to do the tedious and time-consuming negotiating.
I also left "Reset Prevention" OFF. This is to avoid the game saving after every single match has been played. It only takes a few seconds, but trust me, it slows you down and it's annoying. Just remember to save after each season or so. You're ready to continue.
When all the messages are out of the way and you can begin, go into your "Gameplan" section, and "Assisted Settings". You need to tell the game how to manage your team for you, so you don't have to. Change Lineup to "By Form" or "No Preference" (so the coach doesn't run the same 11 players into the ground), likewise set substitutions to be automatic and so on. There are various levels of this and a few other options regarding tactics, but it's all pretty self-explanatory.
You're ready to begin simming matches! It should now be just a long slog through the seasons, mostly without even leaving the menus.
Obviously, try not to get involved in domestic or European cup games. With this in mind, choose a team who tend to lurk around the middle of the table, too good to be relegated, but not good enough to qualify for Europe. If you do have to play a cup game (you'll have to play in the first round of the domestic cup at least!), don't bother throwing it, it's far quicker to sim it even if you happen to win and have to play another.
After a season or two, I also chose to upgrade my Doctor and Trainer (via the "Operating Costs" section), to help keep injuries down. You can keep upgrading your staff like this through the seasons to help things run more smoothly. As long as you are earning enough money from sponsors etc to cover costs, this is fine.
If you've done all of the above, all this adds up to a fairly short season. You'll probably have to sim around 35-40 games, and you only need to intervene and play a game or two if your team is in trouble, i.e going to be relegated. I'm not sure what happens if you are relegated to be honest - I just avoided it!
Remember if you didn't enable reset prevention, you should save every now and again (I saved after each season).
FYI, I did all this with the Dutch side VVV Venlo (you could use Heerenveen or FC Twente or another such middling team). I did it over 2 sessions, a total of about 6 hours play, and the achievement popped at the very start of the 2019-2020 season. Have fun!