Several years ago I attended the NRA Law-Enforcement Tactical Shooting Instructor School. This was a week long school which covered a lot of material intended for those who teach law-enforcement officers firearms skills. During the course of that week, we were supposed wear two holsters, one on the right side and one on the left side. We only had to wear one pistol, but for certain courses of fire the class instructors would announce that all of the shooters would be right-handed or left-handed for that particular course. That was why we needed a holster on each side.
A lot of firearms instructors have their students do at least some shooting with their nondominant hand. However, this was the first formal class I attended in which we were required to draw, shoot, reload, fix malfunctions and do all other operations from either side. I picked up several valuable tidbits during the five days of this class but one of my major takeaways was the wisdom of having everyone work with those two holsters. Many instructors require their students to do at least some shooting with their nondominant hand. The most commonly cited reason for this practice is the fact that people get hit in the hands and forearms so commonly during exchanges of gunfire. The famous FBI shootout in Miami in 1986 is a classic example. There were a total of nine people actively involved in that gunbattle; two bad guys and seven FBI agents. During the course of the furious gunbattle five of those nine persons were struck by gunfire in their hand or forearm. That's over half the people involved. So, obviously the need to be able to shoot the gun with your nondominant hand is a useful skill.
What about having to draw from the holster on the nondominant side? Reloading and malfunction fixes while using the nondominant hand as the primary? Well, there are actually two really good reasons for that. First, the vast majority of firearms instructors are right-handed, as are most of the population. About 15% to 20% of the student base is left-handed, however. Having to actually work the gun over an extended period of time with the nondominant hand gives the instructor a much better understanding of how his left-handed students will have to function. Most handgun designs are set up for use by right-handed people and may require some adjustment in technique to operate them efficiently with the left hand under combat conditions. The instructor should be familiar and comfortable with these operations so he can teach them to his left-handed students.
The other reason is that as we go through life Stuff happens. I am right-handed. A week ago I had surgery on my right hand and it is now in a cast and will be for another week or so. For a few weeks after that it will not be operating at 100%. I cannot use my right hand to draw, shoot, or perform any other task requiring any manual dexterity. Fortunately, I had Tony at JM Custom Kydex make me a left-handed version of his excellent IWB holster that I wear everyday. I ordered it well in advance so that I would have it in my possession when my hand surgery took place. For now and the near future I am left-handed, wearing my gun and other equipment in a mirror image to my normal set up. Having already spent time learning to draw, shoot, reload, etc. with my left hand, and having proper left hand equipment I can now just carry on my normal routine without interruption. Since I have the same gun I normally carry the only adjustment I have to make is drawing and operating it with my left hand, something I have prior training and practice doing.
Whether you have a problem with your dominant hand right now or not, I would urge you to acquire a holster made to wear on your support side. Then if you have to have hand surgery, you sprain your wrist badly, or you break your arm you'll have on hand the gear you need to continue to be adequately armed. Once you get your nondominant side holster do some practice with it, including some dry work to clean up and speed up your presentation and some live fire practice including shooting, reloading and fixing malfunctions. One day you may be glad you did.