You can argue or over think this one all day. There are pros and cons to either side, and in my opinion it really comes down to what you prefer. My experience tends to be more in extras clubs, as that's what's common in my area. But I don't think it makes a whole lot of difference, at least in this particular topic.
Given your assumption that the level of intimacy will not change by focusing on one dancer vs spreading your attention among half a dozen, it really then boils down to your preference. If you value consistency and familiarity, one girl would be better. If you value variety, obviously going for multiple would be better. But I don't think that's a fair assumption. As others have said, loyalty has its befits. I've found that showing some sort of loyalty towards my favorite stripper prompts to her do the same in return.
I tend to walk the line a bit, I'll usually have a favorite at one club that I'll see OTC & ITC, for the most part to the exclusion of all others at least when she's around. Then I'll have another club where I'll kinda spread it around a bit. That allows me to sorta have my cake and eat it too. At one club, I've got a fave stripper who'll go above and beyond to keep me as a customer. In return I show her the same courtesy. And then at another club I've got a handful of girls that I see often enough where they'll treat me well but they aren't concerned about jeopardizing the arrangement and we're not doing anything they'd have significant privacy concerns over.
It serves two purposes. One, I can choose what I'm in the mood for. I have the fave, I can usually call up for OTC or make plans to see ITC. Or I can pop into her club if she's there. I can also go to the other club, have a few drinks, laughs, and if I choose a couple table or lap dances with a few different girls. The second thing is it allows me to have those second group of girls on deck. We've got a rapport, a level of trust and mutual respect. It wouldn't take much to promote one of them to a fave. I have to mostly cut off the others and reestablish bullpen at the other club again to do so. But it works for me.