I didn't keep a good data book until I became an Expert. I think that before that I was far too inconsistent to glean any knowledge from it. After becoming an EX, I used the data book at 300 and 600 primarily and that (along with shooting Smallbore) brought me to Master. Sometimes, I would just start seeing a trend in my 600 strings and because it was in the book I would see it and make a correction (like sitting on the left or right side of the 10 right instead of dead in the center of the x). Sometimes your NPA will look great, you have the wind down and everything, but for some reason you are putting them just a hair to one side. That's when the book jumps up and slaps you. It'll say, "look dummy, move your sights!" Maybe it's just something weird with your eyes or brain that day. It can change a low 190's score to a high 190's score quickly.
A different book per gun? I'm not sure. Perhaps I would skip pages and make sure that I only had one gun per each piece of paper. That way if you sell a gun you can give the guy those sheets as proof of how well the gun shoots. As far as the shooting aspect, I think it is better to keep it all in one book. I would keep an XC book seperate from a LR book, but that is a given, anyway.
Shooting well at 600 is as much about rythm and confidence as it is about technique. Of course, you won't have the first two until you prove to yourself that you can shoot it well. First of all you MUST be able to call your shots. If you are seeing a shot marker where you didn't expect it, then that is your #1 problem. All your focus should be on where that shot is being released. Closing your eyes won't help, and if you're doing that then perhaps you should do some dry firing. (Side note, some FINE shooting can be done with eyes closed, but you have to have your NPA and postion down to a T first.) If you are blinking as the gun goes off, you are probably flinching, and that's why you get unexplained hits. One thing that will help is immersion. Shoot so much that your body forgets the bang and the recoil. Consider yourself a firing device or a rest for the gun only, and let it do it's own thing. Just as a construction worker doesn't flinch when using a jackhammer or impact drill, you don't need to do it either. Once you start calling your shots regularly, and you see a few 10s in a row, don't stop to think about it. Watch the conditions and knock it down as soon as that target hits the top again. For me, I pop a round in the rifle as soon as I have fired (don't close the bolt yet). All the while I'm waiting for the target to be scored I'm watching conditions and making minute adjustments in the sights, ready at any moment for the target. That way as soon as the target comes up I knock it down again. Your task, once you can shoot 600 well, is to try to keep the target down in the pits all the time. The faster (as long as you are doing it correctly) and more methodical you can make your shooting, the better you will get. I don't know of many Masters or above that take more than 12-13 minutes for their 22 shots, unless there is some WEIRD wind going on.
My critique of your drill:
My normal 'drill' is to
CHECK THE WIND FIRST, LAST, AND ALWAYS
put the gun up
Check NPA now.
, check the wind (if I remember),
ALWAYS remember.
check NPA,
do it again.
take the shot,
CHECK THE WIND to see if it changed from right before you fired, make a mental note and apply this when your target is scored!
pull the gun down, grab another round, toss it in
don't close the bolt
, write down my 'call', watch thru the scope for the target to come back up
AND WIND CHANGES
, plot the shot once it comes up, put the gun back up, close the bolt, etc.
CHECK THE WIND
Check NPA once more
Deep breath, slowly release until your front sight touches the point you are aiming at, stop exhaling (this should have been aligned with your natural respiratory pause during your NPA setup, btw) and touch her off, watching the front sight intently.
As soon as the recoil stroke is over, drop the rifle butt and get your head in that scope for a change in mirage.