People spend their time at a shoot in one of two "modes"; shooting, and not shooting (aka waiting to shoot).
If we want to reduce the overall time taken but we don't want to reduce the time each person is allowed for shooting, then logically the only way is to reduce the non-shooting (waiting) time.
That means more people shooting at the same time, however that is achieved, more lanes or divide each 2 shot lane into two.
From the local GPs I've been to, I get the impression that most shooters finish the lane comfortably inside two minutes. So maybe - subject to WFTF or whoever - cutting the time allowed won't save very much. Although it has to be said, the speed of the shoot will be governed by the slowest person, if you always shoot the lanes in sequence.