Andy, I suspect the headphone knobs on my Scarlett 18i20 are the same size as yours, and I see your point. On mine, I have three such knobs all next to one another.

Yes, if you have hearing issues, using headphones make more sense. I don't recall if it was about you, but we did have a long discussion here about that and someone here works in that field. All I can say is, whatever method you use can be made to work if you learn its limitations and test your mixes on a variety of sources, one of which must be traditional monitors (others include cars, boom boxes, earbuds, iPhone speakers etc.). Headphones are particularly best for checking the stereo field (left to right, mono, noise canceling) but are particularly bad for getting the bass levels right.

BIAB 2024 Win Audiophile. Software: Studio One 6.5 Pro, Swam horns, Acoustica-7, Notion 6; Win 11 Home. Hardware: Intel i9, 32 Gb; Roland Integra-7, Presonus Studio 192, Presonus Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors