Well, Sam has some flexibility in its GCD windows because of Hakagure. And GNB just sticks theirs in their buff window, since it's not part of a rotation. But I get what you mean. A duration roll-over mechanic would be really great!
I think a big part is, if you're trying to greed GCDs, Thunderclap is going to be much better for dodging an orange circle. If you're about to head into downtime, it's fine, but that's so niche. The idea of a Finisher, too, is incredibly niche. Niche abilities can be fine, but I feel like SSS is just a bit too niche. Things like the ranged attacks on melees feel a bit better, as you're forced out enough in fights to make pretty good use of them (now that they don't break combos). I guess without a ranged attack, SSS can kinda fill that hole (if you're only out for 1 GCD). EDIT: but in the same vein, Meditate, and potentially even Form Shift are also filling that role. IDK, it seems like a lot of tools all trying to "fill downtime".I'm not sure why people are so opposed to having finishers/pre-disengage tools... It's like people hating TK in its 4.3x heyday on principle rather than because they play at high ping. SSS only needs to be tuned faintly higher to see far more usage and it's already a decent tool.
Yeah, I got mixed feelings now about Anatman. I saw one of your other posts where you point out that changing Anatman to open Nadi is bad because Monk is currently balanced around PR not being in burst windows, and that that's a good thing because it makes the class more resistant to de-syncing.Slap Chakra generation and a Form Shift onto it, so that it doesn't lock out other uses of the GCD during downtime, and it basically would be that already. And I don't think you'd want to make it a server-tick channel you want to fish for, which tying further power to it would likely cause. Extra power sounds great until you're balanced down for gaining it and its usage is pure clunk (see ShB Anatman openers).
I think it could maybe do a little more (maybe suspend+grant Leaden Fist), but totally agree that whatever it does, it can't be optimal to fish for server ticks. The GL stack fishing was bad gameplay in my mind, and was one of the things that turned me off to monk until GL was turned into a trait.