fremont,
Think of it this way, when you shoot an IDPA or IPSC stage, you are under pressure from the clock, and your peers, to a certain extent. Mostly the clock though.
If you are in a SHTF situation, you are under pressure from a different clock. In that case, you are trying to survive for as long as possible.
While IDPA or IPSC matches are no substitute for experience, either can "help" you maintain your cool under pressure. If you approach the stages from a tactical standpoint, rather than from a game standpoint. Your stage times will likely increase but, your SHTF survivability will most likely increase.
If you end up out in the open, with a dry gun, what do you do? Try to execute a speed reload? Find cover? Reload on the move? Assess the situation and go from there? Personally, I think I would try to do all of the above, at the same time.
I said all that to say this, use the clock pressure as a training tool but, DO NOT think that you can shoot in these matches, and be able to go out on the street, and preform as well. IDPA specifically states that their matches are no substitute for proper training.
Steve
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"Not having thought what should have been thought, not having said what should have been said, not doing what should have been done, I beg thee forgive me, O Father." paraphrase from the 13th Warrior