I think it depends on you and your mates. I did one with a friend who has a different riding style to me - she's consistent whereas I'm more of an over-excited puppy so I'd dart ahead, start flagging, drop back, ride with her for a bit, ride on, start flagging ... etc. But we waited for another at the top of steep climbs and when we started to get hungry (we took sandwiches and sweets to share). It rained towards the end of the day and I got rather cold so we didn't finish together as I pushed on to keep warm. Other than the cold finish, I liked riding that way as we saw each other often enough to share the good times but neither had to feel guilty about being better on the climbs (her) or able to push on a bit more on the flat.