I too am a huge believer in breadth-first learning rather than depth-first, and my reasoning is the same: in my experience, ideas need to stay with you for a while before they take root in your mind and you get used to them.

The big ideas in any Mathematics subject are usually very few. They can be covered at a high-level in a few classes before going into them in detail. This also gives you a broader context for you to place the details as you come across them.