Goat wormer is a liquid, almost like milk. You worm every 3 months.
Worming should never be done on a schedule. Only as needed based on fecal exams showing a high enough parasite load. The practice of worming just because X amount of time passes is how resistance forms. That and underdosing or using the wrong wormer.
Current livestock evidence based medical research supports worming only as needed.
Parasites are never fully eliminated. Their numbers are merely controlled.