Memory is a little fuzzy, but my recollection from the 60s was that in precision radar controlled approaches, 1/2 rate turns were expected once on final approach.
Another use for 1/2 rate turns were holding for a jet penetration at FL200: a standard rate turn would give an excessive angle of bank, particularly in a century series fighter.
BTW, a good GCA would give accuracy as good or better than Cat 1 ILS - a good thing, as sometimes in Europe an F86 pilot needed to get to the equivalent of Cat 2.5 by GCA, with no fuel for other options.