Since I'm a broke college student, I mainly shoot my .22LR pistol and rifle. Sure, I have the "Fat Man and Little Boy" pairing of the 10Fp .308Win and Mk.II .22LR; and .45ACP 1911A1, as well as a Ciener .22LR slide. Shooting .22LR isn't the same, but it saves HUGE amounts of money, and still sharpens basic skills. In addition, the .22LR has virtually no felt recoil, so you don't develop a flinch while shooting. The following is an incoherent rambling of things I've picked up about .22LR practice sessions:
First of all, .22s have a lot more grunt than you might think. A month or so ago I killed a starling at roughly 120 yards with a single round of Federal Champion 40gr lead round nose. I have started regularly practicing at 100 yards and beyond with the rifle shown above. The plain jane 4x scope is about the be replaced by one with target style adjustment turrets so I can practice adjusting for elevation and wind with more than just hold-over or hold-off. While I don't recommend shooting small game at ranges over 100 yards, the .22 is lethal at those distances. I've heard tales of old men shooting two liter bottles at 200 yards with custom made .22LR's. What's the point? You can get a lot of quality training/practice out of a .22LR. This can save you money or time at the reloading bench.
I bought a Ciener .22LR slide for my 1911A1 in May. I've put about 1000 rounds through it so far, and I love it. It works flawlessly (or nearly so) on my Springfield Armory 1911 frame. I use the .22 slide for all of my practice. My double taps have become infinitely more fast and accurate. Best of all, because it is the same pistol, I am just as fast and accurate with the .45 slide. God knows how much money I have saved by shooting .22LR instead of .45ACP.
A word on ammunition
I have used a wide variety of ammo, and can tell you that there is indeed a difference. If you are looking to get the most accuracy out of your rifle, use the same type of ammo every time. I shoot Federal Champion high-velocity 40 grain lead round nose. It feeds well in my rifle, and is very accurate. I have also used CCI 40 grain standard velocity with great effect. American Eagle 32 grain plated hollow point high velocity is a close third place.
I consider "Hyper Velocity" and "Subsonic" rounds to be oddballs. Both tend to be very expensive comparatively, and not a lot more useful than cheaper loadings. I have used CCI Velocitor, and keep some on hand for big, particularly nasty critters like possums or coyotes at uncomfortably close range. Velocitors are very accurate and should pack a decent punch, according to my muzzle energy calculations (Velocity squared x bullet weight /450436).
I also tried some Remington Subsonic rounds, and found out a lot about the sound barrier. A lot of widely available SS rounds fly at about 1050fps. This is only subsonic at certain altitudes and temperatures. They are not much quieter than standard rounds. The "advantage" is that subsonic rounds never cross trans-sonic turbulence, hence, they are said to be more accurate and are popular at matches. If you are looking for a quieter round, use.22 CB Long. It shoots a 27 grain bullet at 710 feet per second. They are nearly silent (quieter than my 1000fps BB gun), and have a very short effective range. I would not hunt with them, and they drop FAST past 15 yards. This load is great for teaching new shooters. The lack of recoil and noise builds confidence and reduces flinching or jitters.
If you're looking for a way to polish up your shooting skills, why not go with a .22LR? Pick a rifle or handgun that mirrors your full size rig, and shoot more! Shooting with a .22LR will improve all your basic skills; and in shooting there are no advanced skills, merely advanced applications of basic skills.