E1S and E2S are in a good place difficulty-wise I think, a solid first step up from EX trials. Not every mechanic is beyond the EX trial level, but many definitely are, and for an early fight that sort of mix is fine.

By the third and fourth fights though, we should have mostly left the EX stuff behind. Yet there's been a pattern of lengthy filler, most noticeably in the fourth fights. Sequences of a minute or two or even more, where nothing that happens is any harder than a bread-and-butter EX trial mechanic.

Leviathan does really nothing of note until Stormy Horizon. I was baffled that there was no even-moderately-difficult Maelstrom. Titan has a long second phase full of largely rudimentary stuff, save for the Evil Earth combo and maybe one or two raidwide damage spikes. Final Omega had big dead periods between each Hello World and the next Patch. Omega did a bunch of nothing stuff in phase 3 before Pantokrators. And so on.

The difficulty of later fights has been very isolated into two or three sequences or one or two phases, while the remaining majority of the fight is just going through the motions. Even TEA is like this, although the difficulty of those harder parts is of course higher.

This is silly; while obviously it would extend prog and clear time to have more hard-stuff time in fights, that seems better to me than purposely making fights lame for large sections. You're already asking players to be able to execute at a certain level, asking them to do so for 70-80% of a fight instead of 30-40% shouldn't be too big of a reach.