Arm guard? Defiantly, no.

[styksnstryngs]

Do the Olympians know they don't need to wear an arm guard if they had proper form?
Been at this for 60+ years and always wear one.

There are actually a number of very elite archers that have their shot cycle consistency down to the point where they are barely grazing their armguards on every shot. This is the limit of front arm extension, basically. For us mortals, I wouldn't recommend going near that point, but an armguard can't hurt if you do tend to shoot on the more extreme end of alignment.

[dragonheart]

I know we are a trad hunting primary site, but if you just look at a target recurve bow set up with the most stabilization, and one of the best target archers to ever shoot an arrow, he wears an armguard.  It just gives protection and is functional for clearing a path with clothing.  Why not wear one?   

That is a 900 buckle meaning he did what no archer in history has ever done with a recurve and consistency.
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[carpenter]

 I am diabetic and always use one, better safe than sorry.

[black velvet]

Only when I am hunting in cold weather to keep my sleeve contained.

[Terry Green]

No, I don't ever wear one. With my wool vest and Grey Wolf Pull over in the winter are no problem.

[TooManyHobbies]

I sometimes don't wear one for practice, I always wear one while hunting.

[Wheels2]

I try to remember to take one with me to keep the sleeve out of the way.
But too often I leave it at home, so now I just keep a bunch of rubber bands around the hood of the bow quiver.
Not as good looking, but they work just as well and I can use them to add a few branches to the treestand rail to help with outline.