When I first began writing I used to love jumping around to different character's point's of view, not just in the same chapter without a break, but on the same page (cringes). Some of my old favorites did it so I figured, why not me? One of those old favorites wrote the original Dune saga. Yes the very one which you either love or hate and a vast majority of book lovers won't read because they can't follow it. It dawned on me after many years that jumping around POV's is why many readers can't follow Dune. One must be advanced and a little brilliant to jump around POV's in the same page, like Herbert. Lesson learned. Thankfully, I learned that one quicker than the adverbs and adjectives.
My latest lesson is voice; the cadence, flow, and choice of words (and over-use). This has been perhaps my most sophisticated lesson, the one that took the longest to absorb but that touched my writing the deepest. Writers the world over are taught to find their voice and it is whispered of like some mysterious thing. But that's all it really is; cadence, flow, and choice of words. Part of this is simply in the way you prefer to speak and write, and part of it is in learning a better way to write (varying sentence structure for better flow,~and to suit genre~choosing the right words, and not over-using words.
How about you? How has your writing evolved over time?