Ayin, I have one that's personal for close friends and family only. That way nobody needs to hear my rants nor see my vacation pix but those who tolerate them well, LOL. However, that one has the most friends since it's been around a long time.
I have one that is for my art business and solely for that reason. I want to post only those things that will potenttially bring viewers and maybe sales. That has only a few friends, because it's very new. (FWIW, having used FB boosting for work for years, I'm not at all convinced the investment brings new viewers, so haven't committed to that.) I have one for our plein air painting group, on which I can't push my work nor my website too much as it wouldn't feel fair. That's 3.
Similarly, I have one blog that's for family and friends on blogspot.com, another on my website on weebly.com that's for art viewers and interested parties, and I am careful not to mix the motivations.
While I do post some of the same art content between those different audiences, I don't want folks on my personal site to feel pushed to push my art for me. I hate when others do that to me, whether it's their chain emails/memes or similar demands, so I don't do it to others. So I'll only suggest gently and infrequently about my art site on my personal sites.
Due to the way FB delivers content, if I post it on one site and refer it to another, I'm often seeing double or triple of the same post, which I find confusing and annoying and am hoping that others don't feel that way. That's what I've been trying to straighten out.
Does that clarify it a bit?