That's because except for Dancer in some situations, no job is anything but "static rotation". What a proper gauge management would entail is that your inability to ever optimize your gauge perfectly leads to minimizing losses, usually achieved through:
* Having multiple resources.
* (Ideally) trying to spend one accelerates generation of the other.
* Few/None of them produce truly reliably. High proc chances for example, but there's a chance you won't get an increase. Or maybe it always adds +X~Y charge, in a certain band.
* No way to spend multiple resources in quick succession.
This means avoiding overcapping is an impossible thing to truly perfect. Now as long as those spenders are GCD based, we're getting into non-static-rotation territory. Your gameplay cannot be static, as you cannot know before the fight how the procs, randomness and their timing in the fight enforce which resource to spend when versus which you allow to overcap when.
And yeah, except Dancer around their burst, no job currently does this. They're all too dependable and too staticky in their main rotation and also how their spenders integrate (oGCD weaves instead of GCDs) to eshew their statick-y rotation.
Viper would be really fun as a highly randomized job:
* left/right truly random, no predictable sequences at all. Just react to the swords lighting up! In return, positionals either totally removed or the whole sequence is random side or read after an Awakening, until the next one (as in, Awakening flips the coin whether you're side or rear now).
* 2H mode is also random in which you use first for extra damage. Hence it's still either side->rear or rear->side, but you got to react on the spot when you start it.
* Gauge generation is unreliable, as say the right combo adds 2x as much as the left one, and with them being utterly random, there's no way to know how quickly you build gauge or not and hence whether you'll have to bleed some off in what moment. Bonus points if the right skills in turn only give 6-9s of the self-buffs, and the left give 2x as much or so. Meaning that either your buffs are tight or your gauge, or something in the middle. And you cannot plan or know which it'll be.