We all have our own comfort zones when it comes to playing. There is no fast and hard rule for us. It is all about the moment. We don't always want to form a close friendship with the couple (can be too complicated) this is after all about SEX.
House parties are great as you can hook up with a couple, party and not have to worry about the where and when of planning dates.
I have had a few of the type of relationship originally described, "the dance" can go on a long time and the "moment" may never be right. It only takes one person to get the party started, why not be the one