I'm assuming a full round robin wasn't their priority considering how long the actual season is and that stages only mean something when you look at the extra title matches they hold.
I just want to re-iterate that to keep their current format of:
- 60 total matches per stage
- 12 matches per week
- 4 matches days per week
- 3 matches per day
- 2 matches per week for each team
To add that 11th match for each team you need to spread an extra 6 matches over 5 weeks. Their current format doesn't allow for this unless they add a 6th week with 4 matches days, with 2 matches each. Each team would play once and the last day could be reserved for title matches. This only works if they're willing to have a lighter 6th week and what ever implications that would entail.
Other alternatives would see you break the current consistency of the schedule by adding an extra match to a team's day somewhere in the stage which would make for an uneven spread an an extra long day that wouldn't even be equally spread over the 5 weeks. IMO this is just as unfair as some teams not getting to play other teams during a stage.
Also keep in mind that this season is long. Each team plays 40 matches and with a total of 240 matches, not including playoffs, there should realistically be a large enough number of encounters for each team's theoretical ranking to match their actual one even if they didn't play those 4 extra games.
This is the first Season so iterations are possible, I'd even say probable.