I can't speak to WHM/AST, but SCH sure. For the most part I can keep all of my spells/skills on 32 buttons / 2 crossbars.

SGE seems fairly condensed already. My only really thought would be to make Rhizomata appear on/over any addersgall ability when you don't have any charges...since otherwise those buttons are just greyed out anyway when you don't have addersgall.

With SCH make the Summon "insert fairy" button turn into Dissipation once the fairy is out. Also while we're at it...no point in two fairy buttons on bars anyway since they do the same things now. Pretty much just pick your favorite flavor fairy and place it on the bar anyway. Be kinda fun if the fairy swapped randomly between Eos and Selene when summoned/Dissipated/Seraph summon ends (or even based on Eorzea time). Heel and Place should be one button. Aetherflow and Energy Drain should also be combined.

Repose is pretty much never used and just filler, so that can go for all healers. Only have it on my whm bar to fill button space.