I agree that solo players & small groups(duos) are disproportionally affected by the Shift change(nerf). I'm sure the argument could be made that this change affects parties of any size (as intended), but if the design decision was made looking at it only from a large group perspective, I could see how this change made logistical sense to challenge a well balanced group to have to now consider casting an extra shift per combat while the rest of the team hold down the fight.
Lets expand on this conversation to explain what made RatLabs decide to make this change now, and what balance adjustments can be made now that it is being sampled by a larger demographic. Legacy Shift wasn't great and we don't want to go back to requiring casting in combat only. Being able to cast and extend Shift before battles had become a necessary routine for all ranged combatants (wizards, throwers, some adventurers), and was somewhat taken for granted; I would assume an average character casting (pre-nerf) ext/shift would get 20+ Rounds.
Is 20+ rounds excessive? Maybe. It did create the mentality of cast it and forget it. I preferred the round method vs. 'on hit' method as you didn't really have to keep track of it swing by swing (at super fast F12 speed). But just cutting the amount of rounds would disproportionately affect longer fights vs. shorter fights; keeping in mind larger groups will finish fights faster too and less likely to run out of 'old' shift.
Changing Shift to a 'by hit' model isn't necessarily a bad thing, I just don't think they've hit the sweet spot yet. 15 hits is simply not enough for an average player.
In theory, this new Shift change could last More Rounds, or could be eaten up in one round depending on the mob(s) and your team size. So they did their job by making players be mindful of their Shift stat, but it shouldn't be the most important thing that makes or breaks a fight now.
I think the main difference is that if you are in an high end dungeon with 4+ characters and 1 of them is targeted, you can plan to cast the extra Invulnerability or Shift while the other characters control/heal/draw mobs attention. So the mindset of making it harder for larger groups in these new fancy AI dungeons to make Shift a factor to consider isn't a bad thing and the 'by hit' method may even work better for that.
..But as OP and others have stated, the 15 hit model is not favorable to solo/small group/lower level players. Wherein it is adding a (necessary) challenge to larger end-game group content, it now also penalizes other styles of play disproportionally across the board. Since Shift isn't a guaranteed number of rounds anymore, we cant be as flexible with our round by round decisions, knowing that any round we are targeted will likely mean the difference of being able to heal or hold or shift and choose wrongly and die.
The main difference for solo/small groups is that you are getting hit and you are losing your shift much more frequently then if there are 5 other targets.
My suggestion for balancing Shift better, is to look at it like Invul. Invul lasts a decent amount of 'rounds', soaks up the expected amount of hits, and needs to be recast frequently enough to not feel like a huge burden. Before, Shift was a non-thought. ..now you run the risk of having to cast it every other round in some battles, which by yourself means doing nothing else=you lose.
Make Shift last as long as Invul. It actually balances the warrior/wizard (and don't forget us thief throwers too) out more by fixing our defense spell to mirror/match the tank defense spell. I'm still not in love with the idea of having to squint-track how many shifts I have left, but it will cut down in the amount of times shift will need to be recast for solo/duo players.
..Sorry so long, not to hijack the post, just seen a lot of talk for or against this topic on both Channels, some people really upset and quitting, and though I am doing my best to adapt, I haven't been as excited to run harder content with my solo or duo group lately and i'd attribute it in part to this change.