Originally Posted by
chaadster
The 48/15 is smack in the middle of the cassette, perfect for heavy use, whereas the 35/11 is next to last on the cassette on the small ring, which is perhaps handy if I were to have one of those fits like the 1x guys have where they can’t figure out how to use the front derailleur, but more likely, it’s useful in short, sharp rollers or when a climb briefly flattens out before pitching upwards again. I don’t think I use 35/11 much myself, but scrapping all the benefits of the 11 other gears to get rid of a the so-called “duplicate” 35/11 makes zero sense for how I ride.
The point is, the 35/11 isn't the only duplicate gear in your setup. There are several duplicate gears, which is why you effectively have only 15 or 16 different gear ratios. The only way to get (close to) 24 useful gear ratios from a 2x12 setup would be with some form of half-step gearing.