Lets say you have 4 Wizards party and you want to cast Mage Armor to each ...
Hotbar:
1. Wizard ... Click on icon > cast
2. Wizard ... Click on icon > cast
3. Wizard ... Click on icon > cast
4. Wizard ... Click on icon > cast
That takes 8 clicks to buff them (11 if you count switching characters)
Pop-up:
1. Wizard ... Click on icon > pick level > click again > cast
2. Wizard ... Click on icon > pick level > click again > cast
3. Wizard ... Click on icon > pick level > click again > cast
4. Wizard ... Click on icon > pick level > click again > cast
That takes 12 clicks to buff them (15 if you count switching characters)
The big flaw in that line of reasoning, is that it doesn't take into account time necessary to organize hotbar after every levelup or change in spell repeortoire. That's an argument against spells not being hidden behind a "folder", not in favour of hotbar design which is incoprehensible mess without heavy maintenence.
Even so, you assume there is no hot bar to begin with, for frequently used spells (which Pillars of Eternity and Pathfinder have - when it comes to hotbars Pathfinder is better then BG3). On top of that something like Pillars doesn't even require clicks as things expand automaticly when hovering over.
Solasta requires only one additional click, Pillars none. I do think Pathfinder is far from perfect, with a lot of wasted real-estate which could be used for an easier to access (or personally, I would happily trade left optional sidebar, for an easier and automated access to the spells rather then expandable-thingies.)
