When are you navigating Ephraim down unpopulated hallways in 5x? I secede your point on 7, although the counter would be the introduction of the ballista that chapter. I am not a fan of Eirika's route as I am Ephraim's, but 11 doesn't have any mountains. Do you mean 12, Saleh's chapter? The lower three rows don't need to exist, but the narrow corridor you have to traverse with those spiders coming down at you from each side. 13 never felt barren with how many enemies swarm you. 17... just needed harder enemies and not a couple dozen eggs.
From what I've seen of Yooka-Laylee, it's a good game. It's major faults were it's a collect-a-thon with old style camera controls [the actual mechanic] and the framerates. It's no rebirth of a genre like Shovel Knight, but it's a step in the right direction. Echoes feels like it's gonna be much better than Yooka-Laylee too.