I wouldn't rely too heavily on conjecture by a television program. Not saying it is wrong- that is impossible to prove. But as far as I know it is conjecture. One could equally well conjecture that the need for an attendant could be fulfilled by a knight's retainer. More than likely they acted as was convenient in the circumstances.
For example, an account of a battle in the HYW between some free companies mreferred to the men-at-arms on one side advancing in a formation protected by large shields (pavises perhaps) to thwart the longbowmen on the other side. According to the account it worked. On a completely different note, like archers, one thing that English men-at-arms were very good at when they fought on foot was using things like trous de loup and abatis and natural obstacles to obstruct the approach of the enemy.
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