There is widespread resistance now for wormers of his group (white wormers), and also as it is mainly used to treat nematodirus - which should not yet be a problem - I wouldn't have thought it is useful right now.
Unless your goats do have an actual worm burden there should be no need to worm. Not sure about fluke burden, but vet could either do FEC and/or blood tests to determine. Depends on your land and grazing patterns.
Do the goats and sheep share grazing and do the goats go out to graze in winter? If yes to both - then an FEC would be my first test.
I don't routinely worm my sheep either btw.