I suspect the reason for this is to stop competitors from policing their brass immediately after a stage. Because doing that would probably mean doubling the time for a match and generate a LOT of complaints about "slow players".

As for technique, I agree with all the others about lots and lots of dry fire practice and developing a smooth continuous trigger stroke. I will also note that you will find the rim of your snap caps will "shoot off" after about 700 strikes, so plan on keeping multiple sets of snap caps on hand.