Two of my most essential pieces of shooting gear are my training log and range binder. My log is what I use to track all the numbers and take notes on my shooting, whether it be in a competition or practice session. I even take notes on dry fire every now and then. The binder is what I use to tote around printable targets like the Dot Torture target and a few others. I also keep at least a couple of my old targets on record in the binder, usually my best ones so I can compare down the road and see actual improvement.
The log is what tells me what and how to train. I can use it to see improvement, see which drills are working, aren't working, or which areas I need to switch focus to. There is a great article about performance tracking over on pistol-training.com. It helps to have some goals to work towards, like my goal to reach master class on the IDPA classifier by middle of next year.
Since I also take match notes in my training log, I can also use it to improve match performance. See what things I need to work on and watch our for at my next match.
Every shooter who claims to "train" should have a log, otherwise you are just blowing rounds down range and really don't know if you are really getting better or just having fun shooting. The two don't always go together.
The range binder is more just for my convenience, and a little cost savings. I can print targets for free, so when I go a range I buy one of their targets, and I may or may not actually shoot at it, or just use it as a backer and put my target over the top of it. I very rarely buy more than one target per range trip. Even though they are just a $1 each, if I buy two or three targets for each range trip that adds up over the course of a year. There are also some targets you just can buy, like the 1" dot target from Range USA Self Defense Handgun that is the bane of my existence.