About the only time I touch the brakes is if I am stopped on a hill. The HST braking works well enough to stop the machine even if I am towing a trailer, so well that you better be wearing the seatbelt if someone that's never driven the thing is driving it. I would be surprised if I have used more than 5% of the braking material after ~1300 hours and 7 years of use.
The brake lights certainly work but they might as well not be there. If they triggered based on the braking in the HST somehow, they would be a lot more useful.