I know lots of people who do all those things and use a designated board for each.
I have three style boards and I use them in different ways.
1. General Style -- I pin ANY fashion thing that appeals to me here. Anything. It's sort of like the way that I used to look at the Sears catalog when I was five. Turn the page, point at the first thing that catches my eye and circle it. It wasn't like I was going to ask Santa for all of it, it was just a way of identifying what was out there and what appealed to me. Now, when I look at that board I get a general sense of the things I am drawn to, from outliers to stuff that is solidly in my wheelhouse.
2. Key Elements -- a VERY curated board that features things I own or the types of things I wear frequently. Everything on it makes my heart sing. This is the place I go when I'm contemplating a new wardrobe addition or when I'm feeling pulled by a trend. It reminds me what I adore and helps me ask the question of whether this new item is truly ME.
3. Style Models -- a handful of women whose style I admire. Sophia Copolla, 60s Mary Tyler Moore, Maira Kalman, Twyla Tharp, Ines de la Fressange, Diane Keaton, Jennifer Anniston (in her casual & business looks, not RC), Audrey Hepburn. I refer to this board not only for the clothes that each woman wore, but because it is a solid reminder that each is so great because she was true to her style self. It is a reminder to do the same.
This has been especially helpful in the last seven months as I am going through a lot of transitions. I'm about to turn 50 and have lost 15 lbs. I'm in what feels like a key moment of my career (mostly I work from home, but I've had a lot of speaking engagements and travel of late). I had to buy a lot of new things and using these boards (as well as great blogs like YLF) helped keep me focused and feeling good about my choices.
Sorry to go on like this . . . probably a lot more than you bargained for when you asked the question!