Instead of wasting 3 slots on a simple 1-2-3 step combo, make it a little more creative:
WHM: Uses a Wind/Water/Earth gcd to charge up gauges that will turn the elemental button into a Movement/Regen/Shield buff respectively after 3 gcds. That means you have about 6 gcds worth to decide when to use the charged up buffs.
SCH: Uses "scan" on a short timer that buffs either its light or dark aspected gcd chain attacks. If you finish the 3-step one button combo, you get an extra aetherflow and can rescan to repeat.
AST: Honestly, the best would be the return of the Spread/Shuffle/Royal Road system but with 2 decks: one for damage and one utility focused. That will keep the job busy enough to just have the 1.5s malefic be the filler as it was supposed to be.
SGE: This one doesn't need more buttons imo but you can spice up it's "rotation" with a lil dancer-style memory minigame: each kardia heal will light up a noulith on your job gauge that represents one of your 4 damage buttons (Dosis, Phlegma, Toxikon, Dyskrasia) in a random order. Once you've healed 4 times with kardia, the buttons will change and light up in order they have appeared and the Psyche button will turn into the finisher. This will reward players that know their hotbars well to quickly press the right noulith button in the correct order
Minimal effort for a little more engagement than 1-1-1-1-1-1-1-1-1-1-1-2-1....
