Mythbusters and Archimedes' solar death ray

This was busted three times: in episodes 16, 46 and 157.  However, I would like to revisit it, and look at one variable they may have missed.  Let us look at the facts:

1. Mirrors (even bronze ones) reflect the sunlight.
2. Reflected sunlight from enough sources can cause the temperature to go up (quite significantly)
3. Precision is required to aim more than one mirror at the same spot.

I think that the first two points have been conclusively proven more than once, including by the mythbusters.  The problem seems to be the last point, and they tried to address it the last time, but I think they still missed out on one variable - soldiers.

The shields were not used by students or scholars in a fun experiment, but by trained soldiers.  Give 500 scholars a longbow, without training or practice, and two hours later you might also conclude that they are useless as weapons of war, as aiming is problematic and their arms get tired.  A result which has been conclusively disproven in quite a few wars...

Get a 100 soldiers, and teach them to aim their mirrors properly for a few weeks (and also to keep them impeccably clean).  Replace the ones that fail until you have an elite force of 100 soldiers that are death ray sharpshooters.  Repeat the experiment.

I think that would change the status to "plausible..."