[hnglt]

> It's quite a bit more efficient to take more courses at once, especially if they're closely related (e.g., topology, abstract algebra, real analysis, ...).

I agree that the interplay between related topics helps me form a more robust of understanding of the material.

On the other hand, it might be worth considering proactive and retroactive interference, (the difficulty of storing similar, long-term memories). The layman's takeaway is that it's generally better to learn a variety of non-related topics concurrently instead of similar ones in order to facilitate better long-term recall.