How does my body know to stop growing a beard (Details inside)

The beard is still growing, but the ends may be eroding. Achieving a long beard often requires care for the beard during the full process.

I think like other hair, each follicle produces a hair to a certain length and then stops and then the hair falls out and starts growing another hair of the same length. Depending on the location, person, hormones, age, etc., the hair may vary considerably in length, nature and color.