MicrostockGroup

No, definitely not.
I've learned a few technical things, like CR and not sharpening (I always sharpened heavily because I was printing out on inkjets).
I've learned that what I like to photograph isn't, in general, what people like to buy.
But no, my photography per se hasn't improved - in fact it's gone backwards in creativity, as my most creative thought is how to photograph something without breaching copyright/trademark/whatever.
(And it's my older photos, often scans taken before I was on micro, which are selling rather than my newer ones shot with micro in mind! So I can't even say I'm a better micro photographer than when I started!)