I don't think I've ever tried just peppermint - I always mix it with something. My eucalyptus mint I have a hard time keeping in stock. I just put out a vanilla mint this week (I actually don't even have it listed in the store yet) and it's almost gone just from word of mouth. Last winter I did a menthol/peppermint/rosemary combo that also sold really well for me (cold season, even though I didn't tout it as a cold reliever people naturally gravitated to it for that use). The only soap with mint that I have had a hard time selling is patchouli mint, at least until I get to a rinky dink little SD town in October and there are a good handful of ladies that buy as much of it as they can. Last year I sold out and took a custom order for more.
I scented on the lighter side up until February or so of this year. I was using FO at .5 oz PPO, and EO at about the same if IRFA (IFRA? ugh, brain fart) allowed it. Last year I started carrying more stock, so it was sitting in my storage longer, and fragrances faded badly in some cases. So I made the improvement this year, and the feedback from regular customers has been really positive on the fresh bars, we'll see how the year goes. I may need to tweak again, or tweak certain fragrances. Of course, I'm also looking into different FO suppliers so all of this is up in the air at this point.
True story: last fall I decided I was going to "rebrand" myself for 2018. My idea looked great on paper, but once I got started, it was not making me happy. So now I'm rebranding back to what I was doing but making some improvements. I've been doing my business for almost three years, and I still feel like I don't have it figured out.