Absolutely! Without a doubt I've become a better angler since I started keeping a log; around 10 years ago. I don't have a really fancy, thorough system; just a notebook that I keep date, weather, water conditions (temp, clarity), body of water, number of fish, where I caught them, cover they were in or structure they were on and baits used.
And almost more importantly, I'll log what didn't work for that day.
Now, if I need to, I can go back before a trip and read what worked and what didn't for the same time period. Doing this has taught me the typical patterns for a given time of year. The thing to be careful of, and this topic may spark a debate about fishing "history" as it always does, you have to fish the conditions at hand. It's just that the log gives you some clue as to where you should start; then adjust your presentaions and baits as the conditions require.