And don't forget 'Follow Through'!
Sorry, I couldn't resist.
My scores are higher, and I don't practice near as much. I honestly think that if I practiced that much, my scores might drop. That said,.. Is there any rational behind that? If I shot 12 timed/rapid practice sessions with some slow-fire thrown in, and matches once a week, A), I'd go broke -Rimfire ammo isn't getting any cheaper. B), I think my arm would fall off. It is amazing how fatigued a shooting arm can get with long shooting sessions. And if you're like the rest of us, we don't only shoot rimfire. And if I throw in cutting firewood and swinging the hammer on the home projects a couple days a week, mixed with any carpel tunnel symptoms I may have from my lax desk job at computer keyboard, my hand gets tired.
Factor any of those possibilities with your current shooting.
Brian Zins may shoot a lot with a properly designed workout regimine, but I doubt he's remodeling his house or digging drainage ditches too.
For me.. (and take this with a grain of salt, but you might try some different things to get you out of your rut).
I've found that shooting my 1911 with a heavier trigger pull, lighter pistol, and more recoil, prior to shooting rimfire, gives me a bit better slow-fire rimfire score. I can't explain it, but I'm sure there are some natural/physical/technical reasons for this outcome.
Last season I fell into a short rut, fiddling with stance, how tight my belt was, (Yeah, don't laugh), where my off-hand rested, to the shoes I wore to a match, (cold feet on a concrete floor, I changed to boots), got me back on track.
Not to mention I brought a different approach to my breathing and concentration. I try to put myself in a zone. Nothing can distract me. And I police myself not to hold too long. I don't rush the shot, but if I'm taking too long, I rest the pistol on the bench and re-approach as a first shot. I got to the point where I could really call my shots. I didn't need to look through the scope to know that last shot was an, 8-breaking the 9 ring. And many times, I just knew that last shot was a 10 -it felt so good.
Remember to change only one thing at a time. Log your results. If the change didn't make a difference, unincorporate it. The links above are great. But be sure not to over engineer your shooting. Have a fellow shooter watch you. Maybe they'll see something you're not grasping. I agree that it might be good to work more on your slow-fire. Personally, my five shot strings are singles with rest between each. Many times, the hand is empty for 15 seconds. Remember, 10rds, 10 minutes. If your first shot is always a 9+, then make every one of the string be a first shot.
Caffein, Cigarettes, Alcohol, all have an effect on our shooting. Nerves, stress? Don't let your shooting frustrate you. Use it as a calming time when the wife, kids and work cannot get to you. Take a look at last season, compared to your current scores. Your shooting routine might be fine, but outside stresses may be impacting your concentration.
-Steve