VItex dosage? Bill? Herbal experts?

Does anyone know why 400 mgs of Vitex (also the amount in M) is taken only once a day? Is it due to the half life? Is there any advantages or harm in using it twice daily?

Yep, to little prolactin may decrease sensitivity in the testes and lower T.
To much Vitex causes it, so stick to 400 mg if you aren´t using steroids, in which case more is ok.