It's always an interesting thing to track one's progress in a skill like painting. In the short number of months I've been doing it, I don't note the improvement between painting sessions BUT if I line up a series of my miniatures in chronological order, suddenly the difference really pops.
As many others have noted, there is no competition. We all develop at our own pace and have different goals (I'm aiming for "awesome mini on the gaming table level".) I love seeing the different techniques and paint schemes that everyone uses. I've learned so much and am constantly adding to my shopping list of different colors and tools for different effects when I'm ready to try different things.