I was raised around guns, and shooting them. I'm a decent shot, not terrible, but not an expert by any stretch of the imagination. I've also had some formal instruction once I got older, and I learned a TON from it even though I went into it with the typical "I've been around guns all my life, this is going to be boring." attitude.
Having done it for over 30 years, I'd say you're well ahead of the curve. Most fail to realize their mistakes. It's human nature, it's really hard to be truly objective about ourselves. You've already acknowledged that as you get tired, your form and technique go first. That's the same for most of us actually.
Are you fairly new to shooting as a hobby? If so, the getting used to the recoil impulse will come with time. Some dry fire practice can help with that also, and you can do that at home with snap caps. Just keep them and your live ammo in separate places so you NEVER get them mixed up. Dry fire practice will help with the shakes too. A lot of that is not being used to holding three or four pounds out at arms length, and trying to be dead steady for an extended period of time. Some light weight training that simulates that will help also.
You've diagnosed one of the problems. So, what I'd do, is once you start to notice this, take a break. It's hot out this time of year, and our bodies burn through more than we may realize. Have a snack, and drink some water or electrolyte drink, not Gatorade as that shit is 90% sugar. Wait 30 minutes. See if that helps, if not, wrap it up and call it a day. You don't want to train those bad habits into muscle memory by continuing to shoot. Better to conserve ammo, and come back on a day you're fresh. "thumbsup"
