[gdl]

The answer to this depends pretty heavily on what you're wanting to program. If you're planning on writing protein-folding software, or CAD, or a database, by all means dive deep into math and algorithms. A typical web or desktop app? Not so much.

A general understanding is helpful to form an intuition about what options are available for a given problem and what the tradeoffs would be, but in most cases you'll rarely have any reason to write the hard bits yourself. That's what library code is for.

That said, if you have an interest in that kind of stuff, learn it! Even if you rarely use the more complicated parts in practice it will give you a solid base for deciding how to implement things, and you'll get a good sense of just how efficient things can be so that you'll be more able to recognize poor solutions when they show up.