Every shooter should regularly shoot their pistol for groups and the sad fact is that most don't. I suspect that many just assume that their pistol and ammo combination is accurate as both are made by reputable manufacturers.
Unfortunately this is not the case.
Most good rifle shooters do this on a regular basis, but for some reason many or most pistols shooters do not. There is no way around this. You have to shoot groups to be sure. Shooting groups is not as easy as it may appear and takes some practice. However, you will need this skill in your toolbox. If, during your practice session, something seems wrong. Stop, blame the gun and test it. You may be surprised. An alternative is to use a Ransom rest, but that takes time to set up, skill to use correctly and you are out of luck if you are shooting a plastic pistol or cannot locate adapters to perfectly fit your grip. My solution has always been to shoot from a rest. As you can see from the photo, I just use a plastic barrel with some padding to rest my hands on. However, I am particular about how I set this up and the height must be just right, so that I can sit relaxed with my arms and hands supported and with a "flat face". It's easy to test whether your position is steady enough; if the sights move, it's not...
I prefer to use a white target face for better contrast and for the target itself I often get lazy and spray paint on a dot. Small enough that it requires the sight picture to be perfect to have everything lined up and big enough that I can see it even when I focus hard on the front sight. Once you are in position, maintain the same grip tension throughout the string. A relaxed grip will require you to adjust your grip from shot to shot and that is not optimal.
This is also one of the very few times that I shoot with a classic Bullleye surprise break trigger pull. I try to eliminate as much of the human factor as possible; the sights are rock steady on the target, the trigger is compressed against the wall and I steadily increase pressure until the shot fires. I seek to call each shot to make sure that I have the same visual feed-back from shot to shot and throughout the whole shot cycle.
Generally I'd shoot 6 shot groups as that is about as long as I can maintain good visual focus with old eyes and dry eye syndrome.
When going to the range with the primary intention of shooting groups, I often bring a "reference pistol /load" that I know is accurate. That way I can test myself before I get started. I’m rarely surprised, but I tend to doubt myself, when things don’t pan out. Over the years I have learned a lot from shooting groups: More than anything, that you can take very little for granted. Some pistols are inaccurate out of the box, especially pared with wrong ammo. If fact, it's not uncommon to see pistol / ammo combinations (especially 9s) that can hardly hold the A-Zone at 25 meters. First Generation S&W MP9s were horribly inaccurate, early H&K USPs would often throw the first shot 30 centimeters out of the group and some Italian pistols (not Beretta) are very unpredictable. Glocks and 320s often shoot OK, but do not be surprised if 10 centimeter-groups are the norm when shooting S&B ammo. Generally I find that Geco is the most accurate of the 9mm bulk ammo around, but again, you'll need to test this in your pistol. I'll often see differences in load preferences in otherwise identical pistols. Sometimes dramatically so. However, it is very rare that I cannot make a quality pistol shoot well, but it may take some work. As the photo shows, this group was shot with my old Colt 1911 Series 80, fitted with a Wilson barrel. Load was a powder coated 200 gr TC bullet and 3,6 gr N310. I do see a small tendency to vertical stringing, but suspect that it will disappear if I up the charge a 1/10. Target is a 50% size old-style target, so don't let that fool you. My Series 70 shot poorly with the same load, but liked the H&N 200 SWC. My Guncrafter American shot both loads well, but prefers 185 Jacketed HPs - which none of the other pistols seem to like that much. An so it goes.
Either way, I am confident that my pistol and load combination are more than adequate for next week-end’s T96 get-together.