I prefer scenes of 4 or less. But honestly as someone who rarely parachutes into a game with a ton of friends, I know too well what its like to have to go to pub scene after pub scene trying to meet people and getting the brush off. So if I see someone new or struggling then I prefer to include them.
However, if they turn around and play hard to get in the sense of not reacting/posing ignoring everything then I let that go immediately. Don't have time. I've learned the hard way that I almost never regret turning right back around and walking out when someone solicits rp ooc and then poses being unapproachable or hostile or too good to pay attention to anyone around them, and often do regret when I stay and try to pull RP out of them. Nope, don't have time for that. And usually when I pose preparing to go the ones that want rp will change their tune and then a decent scene might be had.
I'm a super social person RL but never impose myself or try to lure out people who seem like they don't wish to be interacting. That's fuckinh rude and violating to push yourself on others! On mushes there was this odd pressure to try and chase people for RP if they joined a scene or wanted to interact with the set or gave an ooc indication that they wanted RP or were upset that nobody would play with them and verbalized it. But now unless someone is being an equal giver in the scene I try to not feel like I have to carry things/keep reaching out even when thd other person seems to find a lot of fun in slapping everything down.
I still feel that anxiety about someone feeling left out/excluded but I'm trying to be more like RL and accept/believe a person when they pose being disinterested in interaction regardless of what they might say or have done ooc.