Not that long ago, I was digging through my old papers (moving the OLD old into boxes to put in the attic, so the less old can fit in the file cabinet.), and found some stuff I wrote back when I was 19.
And DAMN did that stuff suck. At the time I'm sure I thought it was, at least, solid. But, really, it sucked. Empirically. Physicists could prove it sucked.
Hell, stuff I wrote five years ago, in my early thirties, sucked.
I can honestly say that the point where my curve started to move away from sucking is when I started taking the process of critiquing seriously.