This game has been pretty hard but also very fun! There were multiple mechanics that I definitely required to achieve max size that I'm not sure if they are intended but I'd love to share my findings.
1) Jumping in air has a lower jump height than jumping on land, allowing players to kill enemies at the front end of buildings by delay jumping.
2) Attacks can be cancelled on hit to kill multiple closely spaced enemies, while punishing players for whiffed attacks with long recovery.
3) Two buildings with the largest gap that couldn't be reached with delay jump > ledge tech, requires a land jump beforehand, thus enemies at the front of the 2nd building for those could be avoided by early land jump > ledge tech > immediate attack.
4) Attacks aren't forward advancing and can't be cancelled on hit immediately after ledge tech or when done in air, thus when there are 2 closely spaced enemies at the front end of the 2nd building after the largest gap, players can't combo them. This can be solved by attacking while on the ledge, that will kill the 1st enemy, allowing players to kill the 2nd one after teching.
Reading through the comments, I believe if these mechanics are intended, better communication would help a great ton. I personally love the difficulty presented right now so I don't really wish it to be changed easier, but if the game is intended to have a more lenient gameplay maybe a difficulty setting could allow different skilled players all enjoy the game, maybe capping max sizes for higher difficulties etc. I do think constant ledge grabbing destroys the side scrolling pace of the game so maybe an auto ledge tech would make the gameplay more smooth. I look forward to further development on this game and I wish the dev the best of luck!