I usually do a simple drill at the range where I load two rounds, fire two aimed shots (meaning not a quick double-tap) with my right hand, load two rounds, fire two aimed shots with both hands, and load two rounds and fire two aimed shots with my left and then repeat as often as I feel necessary to practice technique.
This does a number of things for me.
First, it teaches me to become naturally aware of the difference in point of impact from single handed fire to both hands. My normal point of impact, with a proper neutral two hand grip of course, is about an inch to an inch and a half above the center point of my front sight blade with my sights aligned properly--at average distance. With one handed fire, that POI increases slightly to 3 to 4 inches above my front sight blade due to the lack of support hand reducing the muzzle rise.
This is important because if you're taking a head shot with one hand, for instance, it's possible to completely miss the target altogether.
Another thing it does is to teach my muscles in my non-dominant hand to become more familiar with the necessary grip and what muscles in my hand, wrist and forearm to keep flexed or more relaxed to properly handle the recoil impulse so as to quickly/smoothly line up and fire the follow-up shot accurately. One challenge with one-handed shooting that becomes clearly evident when using your support hand is striving to hold the gun firmly with all the fingers and muscles within your hand and wrist while relaxing your trigger finger enough to have precision control of the trigger.
Another aspect of this for ME, is that I practice using both eyes. Left eye with left hand and vice versa. Not necessary for this exercise to be effective, but I figure you could lose an eye as easily (or easier considering bullets flying, debris flying, etc.) as an arm or hand.
Another thing is the time in between each set of two shots when I reload gives me a brief pause to assimilate what is happening with all the various dynamics of the exercise and correct or confirm certain techniques and habits and remember those corrections when I return to that hold.
Doing this type of low round load exercise also helps to make your ammo last a little longer and to encourage more effective training in the short time we get at the range.
Even 200 rounds of ammo can be burned up easily within a half hour or less if you just load your mags to max capacity over and over and just stand there and blast away--invigorating as we all know that can be.