The Randomizers may be going for record number of dungeons, but length is harder to measure. In Alpha, there are 8 main dungeon sets with an extra final level each, so that's 80 already, with a Light World/Dark World mechanic. Add the lost overworld and it's 9 bonus dungeons. Also count the proper final level. So, main length is 90 dungeons across 3 overworlds. Plus 324 items to collect.
Then comes the postgame. The intent of the postgame was just to have fun with all the items you collected and a fun way to reach 9999 rupees if you wanted. Beta testers wanted a little more than this though, so I hid a super secret dungeon with one last prize. So the final tally for Randomizer Alpha is 91 dungeons, 3 overworlds, 36 optional dungeons, 2 optional overworlds, and one battle tower. Have fun!
Meanwhile Randomizer Returns just broke that dungeon record. 4 overworlds, 144! dungeons across 16 sets. Of course, you only play a single overworld (normally) and 9 dungeons picked from those 144, so the length is more for replayability. Then you add in all the random factors besides the world gen, and things get complicated.
Legend of Pokemon Warrior is a better balance of quality over quantity, but is still big. 332 items, 12 overworlds about 40 screens each, 17 dungeons at least 32 screens each, 20 or so caves/interiors for each of those overworlds, plus some small stuff here and there. And unlike the above Randomizers, these are NOT NES styled. And once again, secret modes can change the rules enough to be a quest of their own.
I think those dungeons from the returns will be on Randomizer Omega
