Does facial hair growth rate stay the same throughout life for males? or does it change or fluctuate for any reason?

Hair growth: Male facial hair goes through changes in growth rate over life. The first is hormone-related at puberty. Amount of facial hair is genetically determined. Facial hair stays in its active growth phase anywhere from 4-14 weeks (growing about 0.4mm per day) before individual hairs are shed with a new hair growing in behind it. This continues for the most part through life but can slow as we age.

Varies: Facial hair growth will change with time. It can sometimes also change as health changes, and certain medications can alter hair growth, as will changes in nutrition.