I've been drawing feet for a month specifically because they're the anatomy element I most often simplify away and I wanted to understand them properly.

The foot skeleton is architecturally complex: the arches (medial and lateral) give the foot its characteristic shape from the side. The toes are much shorter relative to the whole foot than most people draw them — they occupy roughly the front third of the foot in length.

From above: the foot widens slightly from the heel to the widest point (around the ball) and then tapers to the toes. It's not a simple wedge.

The ankle: the medial malleolus (inner ankle bump) is higher than the lateral malleolus (outer ankle bump). This asymmetry is why feet look wrong when drawn with both ankle bumps at the same height.

Practical application: I now draw feet from memory reasonably well in common poses. The specific study period was useful. I plan a similar month for hands in the next quarter.