How often you use beard oil is really up to you. I use it daily and prefer the feeling of my beard with a leave-in conditioner. My beard is about 12 months long. If your beard is shorter, or you live in a more humid climate, then you could probably get away with using beard oil every few days. In a dryer climate, you might need to apply beard oil a couple of times each day.
Beard oil that uses natural essential oils for the fragrance will last shorter than your typical synthetic fragrance-based product. The scent is the strongest when you apply it, and will fade gradually. You’ll also need to take into consideration that your nose will adjust to the scent and make it less noticeable. Check with a friend to see if they can smell your awesome scent before lathering up for a boost.