Highlights can be good to steer Player behaviour.
It’s best for systems that, like AW, have Stats that express PC behaviour: acting in a HARD way looks and feels different than acting in a COOL way. This works if specific moves are ties to specific stats (like AW does) so that by choosing to use a certain stat rather than another the Player ends up triggering different moves.
So my PC is trying to persuade an NPC… I could do this in a thousand ways, but since I have HARD highlighted I opt to Go Aggro on them, resulting in a scene where I rough the NPC up, instead of a scene where I chat and discuss and manipulate and barter.
As this requires conscious effort and might sometimes put the PC in a problematic situation, the system works best with “heavy XPs” (in AW you only need 5 XPs to get an Advancement) rather than ones with “light XPs” (in DW you need an increasing amount of XPs to level up, from 8 to 18)
Then again, in my experience most Players tend to forget about this and just play their PC however they feel at the moment. But as time passes, and they keep NOT earning XP because they play without thinking, they eventually get into the habit of playing in a more aware and intentional way. When this happens it is greatly rewarding for the whole table
But let me tell you why Fantasy World instead uses a mix of other systems
Since the stats represent some abilities/qualities of the PC, rather than a kind of behaviour, the highlight system would not be very effective. Instead…
On a Snag (a roll of 1-6) you get Expedience Points (XP ) that work both as an active resource to fuel actions and moves, and as pocket change that can be converted into actual advancement when saved up a bit.
Some Class moves allow the PC to earn or spend XPs. And sometimes even “Growth marks” (see later).
The End of Session move is basically a little “ritual” that, through a series of questions, has each Player remember and evaluate the session just played and what their PC actually did in it.
These questions focus mostly on a few core PC aspects that drive the whole game forward (the personal Issue and Doubt each PC has).
Any meaningful engagement is rewarded with 1 Growth mark, like if you act to address your Issue, or act despite your Doubt, or act because of your Doubt, or opt to abandon your current Issue or Doubt.
Any major change is rewarded with 3 Growth marks, like if you resolve your Issue or master your Doubt.
Some focus is also given to minor elements, like memorable moments, or coming up with new character details about their Blood and Kin. This stuff gets you XPs. And XPs can convert into Growth on a 5-to-1 basis.
Since you need 5 Growth marks to unlock a new character option, Growth ends up being the “heavy” currency while XPs are a very “light” one, especially because you would need 25 XPs to get the same weight of 5 Growth marks, and the game caps the max XPs you can hold at 10, and you can only ever convert them into marks during the End of Session move, not during play… so you end up learning to spend them to boost your PC actions rather than hoard them.
This leaves Players free to have their PC behave however they like… this is not what drives the themes and drama. Instead the focus is on personal Issues and Doubts, rewarding Players for bringing those into play and, by gradually changing and resolving them, creates emergent character arcs.
There really are many ways to mix and match different “progression” mechanics
It all depends on each game’s unique design goals.