I.... am guessing this is the trade for Augment Transfer Pass at the Limited Class EX-Cube Exchange Shop, which only allows you to trade two class EX-Cubes 10 times per group (four groups: Hu/Ra/Fo, Fi/Gu/Te, Br/Bo/Su and Hr) every month or so?
I find the groupings a little strange myself - normally the game breaks it down as melee (Hu/Fi/Bo), ranged (Ra/Gu/Br) and technique (Fo/Te/Su) after all. With the intention to make Summoner a secondary class I'd have two classes in the same group which would be a little awkward for this particular exchange.
But let's consider how much work this really is: 10 exchanges of 2 class EX cubes needs 20 class EX cubes per month if you really want to get more than ten Augment Transfer Pass from this exchange each month. Now that our level cap is 90, we get 7 EX cubes per overlevel, which means you only need to overlevel a class from the non-main groups three times per month. When the cap increases to 95 we'll get 10 per overlevel and only need to overlevel twice per group.
That's really not a lot of work. You might think of it as more if you don't have any classes from other groups levelled at all, I suppose? But I think most people who've played this game a moderate amount have levelled other classes by this point.
Moreover, you only need a high volume of Augment Transfer Passes if you want to transfer a lot of augments at once. The manual shows that 1-4 augments need 5 passes, 5 needs 15 passes and 6 needs 25. Those are attainable in a couple months with the trade with a maxed-out class in just one group (and other sources like Mission Pass and campaigns).
Only at 7+ augments do you need more (50, and 100 at 8!) and I really struggle to believe anyone has the resources to create the kind of 8-augment items they'd want to transfer without having multiple groups of classes capped. Most of my classes are 80+ and I'm nowhere close to being that rich.