+1
Being able to condense each spell them all into a single hot bar button would be amazing, and much needed.
Whenever I cast Witch Bolt I have 3 versions of the spell on my hot bar: 1st level cast, 2nd level cast, continuous cast (if already active).
I've used this image on another post before, but it just proves that it is possible to implement with existing UI code. Something like this would be a good first solution and very akin to what @Kyekkyre suggested.
![[Linked Image]](https://i.imgur.com/OflRGCe.png)