IC levels are actually quite small, so you can peek slightly at NE, NW, SW, SE and see the vortex to next level. I think you are simply burned out with IC after going through 600 floors so fast 
Do you mean after 640f they actually -are- smaller? Because all the floors I've been exploring, that is -not- the case :V I'd check but... that boss is hard.
I got to lv2500 and the bosses are still wayyyyy too tough, so, guess I better grind more. I could maybe beat the IC one if I was lucky, but... ouch.
Why does kaguya and patchy feel so weak compared to their LoT1 counterparts? expected total defense piercing magic to be really good in LoT2
Patchouli's only damage boost passive is SDM team and Grand Incantation, which is... not great. Incantation is strong, but hard to use with her fragility and speed, and gets outclassed by Akyuu's party-wide boost later anyway. Silent Selene's mind factor is average now, not even half-pierce or anything. She seems to be designed to wipe tons of randoms without running out of mp, even in awakening, but she's the slowest character in the game and it takes serious TP boosting too...
Kaguya also has no damage boosts except her team bonus (until awakening, which only averages at ~17% damage up... unfortunate). Hourai Bullet is stronger than Silent Selene, but Patchy has more Magic. Kaguya's only specialty is piercing defense. It's incredibly valuable in base game, which starts to drown in high-defense enemies later in, but in postgame she's only relevant against the monolith fights, for which you have stronger, more durable, and faster options. With her poor hp, meh damage, void weakness, and glacial delays, she's not that good. Better to use other defense-piercing characters with more general usefulness. Viable, if you run the other eientei members, but not good.
But hey, at least she significantly outdamages Shikieki at Spirit, whilst also covering two other elements! :V (4~5 other elements if you sub Archmage, which is probably a good idea) Shiki's global damage reduction from backrow is something, though. Err, depending on what "elemental" damage means. Everything but void? Or just FIR/WTR/WND/NTR?