Eh, I like em. Race your face off on the weekend, recover, do group ride mid week for speed work, recover, race your face off again. I'll throw a couple of hours of light z2 in front of the ride for some extra volume and turn it into a 4-4.5hr day. Sometimes I will have a specific plan like doing a few blocks of tempo on the front, other times I'll mostly sit in and enjoy the bonhomie. The caveat is, you have to be fit enough for the group ride to not feel like a workout unless you want it to be a workout, otherwise you're basically doing relatively hard unstructured intervals and wearing yourself down.