You can get cheap 5mm LEDs down to 15deg. beam angle, that doesn’t mean it will be the best for a TIR optic. There are LEDs that have a very high cd/lumen number with the 10507 like a Cree XQ-A, but it barely puts out 1W power.

With the TIR you don’t necessarily need an LED with a super low emitting angle because it is designed to collect and collimate the light coming from a very wide angle