It works well if you have good antennas and can control the area around the reader. I've done it using chipped batons, as well as with rfid on the athlete's wrist... Unless you're only doing a couple or the entire event revolves around them, it felt a bit of a waste to chip bibs.
In the end it is just an 8 lap race, don't overthink it... Though maybe drop the Gap in the lap settings from 20 seconds to 15 seconds just to be safe lol.