I worm accoding to eye lid color. IF they are pale to white they NEED a worming. IF they are pink to reddish I do not worm. I check each goat and worm them accordingly. I try to check everyone every couple weeks to stay on top of it especially when it stays wet out for long periods
by worming monthly you can build up the resistant worms and then your wormer becomes ineffective.
If you purchase a generic brand of Ivermectin then yes it can be cheeper then safeguard. BUT You still need safeguard to worm for tapes as ivermectin does not cover tapeworms.