We roll every 15-30 minutes. More in trad game because everyone gets “a turn”, and less in neotrad or story games where one can roll for the decisive stuff in the scene or simply scenes are about one character only. Belonging outside Belonging I never played, but it’s done without rolls. Check it : it’s great !
I’m always going after XP : if it means rolling in a Desperate position, with a big malus, or create opportunities for rolls, I’ll do it every time. That’s where your system can go boink I think.
On the system :
“Yes, and” in Improv and “degrees of victory” in wargames are different. Which one are you trying to do ?
Picking one out of 3 (or 4?) is a neat idea. It’s more or less what BoB does (Yes and/Yes but/No and). Twilight Struggle does this (Yes/No, note how it’s a wargame) with the “China Card”. I like the unbalanced balance the China Card mechanic provides. Also, ticking is one way, but having a card face up/face down, handing a token or a die are all very physical ways of making the rule live (and not forgotten). Like, instead of ticking, having a token cover the zone where the ability is written (or drawn, if it’s heart, head and guts), and when you give then token, the ability is readable, therefore unlocked. Or anything of that sort, really, according to the gamefeel you want to associate with it. Typically : do players get rid of burdensome tokens or do they gain empowering ones ? etc.
Usually, this type of mechanism is used per character, but a pool for players is an interesting approach. It manages positive spotlight (and therefore status) very efficiently. Only… nothing prevents the situation where one player is always last in the pecking order ? Card games and worker placement games offer a bunch of solutions for this, but that doesn’t sit well with simplification. In any case, I’d find another mechanism to tie this mechanism to, so it will sort of handle itself. Like, the one with the more token chooses when they pick.
On the simplification goal : it sets a clear course and you will have many ideas along the project that you won’t keep for simplification’s sake. For me, I keep all these ideas in a text file to make spinning tops, that is, later projects.
On “picking the outcomes”, I’d keep it per player, make rules for “healing one” and “refresh all” that foster the kind of game you want to see (once per night, when you hit your flaw, whatever) without being too deep. Then you can crash test extreme scenarios in your lab, and soon after try it at the table. A system simple as this will be mostly about how the players handle it anyway (think monocycle, short skis, rolla bolla). If some of your fellow-gamers like to tinker with the rules, let them in and try to keep adjusting the system as you go.
On the top of my hair, I’d go with : XP every time you fill your bingo card of outcomes. If you refresh, no XP : that’s self balanced. Heal one “Yes, X” for each extra “No, X” you do : basic Karma balance. That’s crude, but will only be used in fringe cases. As always, uncertainty is a good start, but not enough : without a mechanic or starting situation for it, the stakes should be manually upped. Provided they are, no one will think of gaming the system. It’s like when players start to scratch your trees for fresh paint, they are just falling out of the game (hint : the answer is not fast-dry paint).