In USPSA, I shoot Limited major which means I shoot .40. Despite shooting a heavier all metal gun, there's still a bit of recoil to contend with in comparison to a 9mm. One of the deficiencies I've decided to work on is grip strength. My grip has been too weak and inconsistent to bring the sights back on target quickly and the result is a pattern of Alpha, Charlie/Delta when my targets are scored.
To improve my grip, I've been using Captains of Crush Grippers for several weeks. I started on the 80lbs or Sport model and I'll move to the 100lbs grippers soon. I do 3 repetitions of 10 in each hand every other day, nothing intensive but I can feel my grip improving during dry and live fire. I'm not sure if it's related, but my tennis elbow injury seems to be healing faster. I shot a match last weekend and the RO said I handled the recoil perfectly after a shot a stage with all Alphas.
Out of all the shooting accessories that you can buy, grippers may have the best return on investment when it comes to improving your shooting.