Nah, it's a big minus actually. The advantage of having different types of sanders with different pads by far outweighs the few bucks you might save.
You do know we're talking about Festool paper, right? "Few bucks" is more like hundreds of dollars to have a range of grits/types in different sizes. Especially since the higher grits only come in 100 packs - so instead of $60 for a box of 180 grit you need two of those, etc.
If you're doing this as a professional and consuming a lot of sandpaper the cost might not be a factor. If you're a hobbyist then it becomes more of a balancing game to get the most for your budget.
I'm really happy with my ETS-EC 150 (3mm) and RO150 duo for the bigger stuff. I have a RO90 for tighter areas.
There's also a PRO 5 LTD rolling around somewhere, but that's the one I let my 'helpers' use.
