3:29 PM, Saturday February 8th 2020
The short answer is both!
Seeing how something looks and how something works in its environment are both aspects to the greater concept of a visual library. I often use an analogy of Lego. Doing studies is like buying a Lego set and building it according to instructions. As you follow instructions you learn techniques and ways they work (how things work in their environment) as well as building up your collection of Lego (visual library/stuff to put in your environments).
When using reference I often look up a bunch of images related to what I'm doing, draw some 1:1 copies to get them in my head and understand how to draw them, then start picking and choosing things like proportion, where props go, overall mood, etc. Hope this helps, and if you want any clarification let me know! It's early and I'm not at my most clear mind yet =)