I learned about thumbnail sketches in one of the skillshare classes I took a while ago. The teacher suggested that we draw very small sketches to hash out the idea. Map the elements in the entire space etc. After drawing couple of thumbnails about the same topic, we select the one that we like the most.
I never did any such thing - mostly because I hardly draw that way, where I pickup a topic, think of various ways I can represent it etc. None the less, the idea was fascinating. Thumbnail sketches can be really nice. Teacher actually coloured some of them as well, in order to plan how it will appear in the final sketch.
Today, I wanted to show my son how to draw various trees for his school work. Without thinking, I drew a couple of thumbnails for him.
So even if one does not apply something that they learnt immediately (or in the field where it was meant to be applied) it looks like it is always beneficial. It stays with you, and comes back to you when you need it (whether you know it or not)