Ok so I shoot a Glock 19 9mm for my job, and yes I can hit a small metal plate at 100 yards repeatedly. I have taken a friends 45 and after a few shots to failiarize myself I did likewise with it. I can do that with a pistol in .22LR too (much harder than the other two calibers). So what? This does not make me a top competive shooter does it? I don't compete, but rather I train for tactical shooting events. If I am in a situation at 90 meters or 100 yards and am armed only with a pistol, chances are I will not be firing if I don't have to even though I know I would likely hit a man sized target, or part of a man, at that distance fairly reliably. My guess is that even under combat stress I could do such at least one out of two or three rounds if I am uninjured. Notice I said at least. My accuracy will not be diminished by a factor of ten. If that were true, that combat stress diminshes accuracy by a factor of ten, then even at closer ranges accuracy would be diminished by as much - wouldn't it! Very few would then be able to hit anything smaller than the broad side of a barn! (I must be old with a saying like that.)
You (generic) practice to make these kind of shots realistic under tactical engagement situations only if you are a good enough shot in the first place. Shots at 90 meters or 100 yards with pistols are not usually practiced by most agencies because they are unrealistic even when not under stress. Most agencies don't practice with pistols out to 100 or so yards because they realize these shots would be unrealistic for most officers who simply are not good enough to make those distance shots with a pistol, stress or no stress. They also realize that combat type pistols were designed for closer ranges. Therefore such could pose a liability in that it would be a potential threat to the public. Shots at that distance should be made with a rifle. You should only try pistol shots at that range if an absolute must shoot situation exists, and at that range you would be better off behind cover or moving to cover.
Many agencies do however practice frequently out to 50 yards and virtually all do out to about 25 yards. At those ranges you should definitely be behind cover and shooting from a rest if at all possible. At further distances of 75 to 100 yards if you are not shooting from a rest you are probably wasting bullets if you are an average to good shooter, and definitely wasting them if a poorer shot. An excellent shot will waste some too but be more likely to hit the target, but should be very careful in choosing when to shoot from that range if at all. As to the type of rest to use, the rest can be the ground, your knee, a piece of cover (which you should be behind) or whatever.
Now as for the stress factor: Sure I do shooting like this in practice with and without a rest and hit the target solidly both ways. Yes I agree there is a stress factor in combat not felt at the range. The thing is it does not, or at least should not, make you 10 times worse a shot. In fact there are practice techniques that will ready you to better handle such stress, and they work. Fun houses are great for this but a regular range can work just as well or better. Make your shooters run an obstacle course, or just run 50 yards, then have them walk or run to the firing line, draw at the firing line, and shoot while moving laterally across, diagnonally across, or staright in or out at a field of targets and having to get up and down behind cover as available. You will see heavy breathing in even the most fit shooter after just one magazine of this type firing at only about 10 targets - one shot per target. If you make them go through three mags, reloading as needed and firing three to five shots at each target (moving back and forth on the range set up) until out of ammo you will see lots of breathlessness, sweat, and some shaking too. Shooting like this helps get you ready for the real thing. Make them load one or two dummie rounds in each mag and really see the stress break out as they try to tap rack and engage or tap, rack reengage, strip the mag, reload and renegage (when one dumies round comes right after the next this is the driil) while clearing the dummie rounds. Note one shooter at a time straight in and out shooting - two at most if lateral shooting left to right (never more than one in and out) and one instructor for each person who is shooting at the moment. Muzzle direction and figer off the trigger while moving is tantamount to safety. Use metal plates and other metal targets so they can immediately hear if they got a hit. The range for all this is about 15 yards with FRANGIBLE ammo (but follow the ammunition manufacturer's instructions about safe distances to shoot htis ammo at metal targets).
Those who repaetedly hit the target maybe ready for the stress of the street. Those who miss may actually may decide on their own to practice more It works like a charm.