Bars are cheaper than shoulders.
A bit lighter there, a bit lighter there.
A 36" bar is a bear to wrestle in the tree. Worse 42" (one maple).
I can only remember retiring one 20" maybe, and non- replaceable sprocket climbing bars. I just maintain them.
Oh, there was that maccoughlah (sp) that got a crooked bar falling when the water knot on my lanyard came loose, at 50', on my first sidejob right after moving to WA and climbing in my rock climbing harness.
My accomplice was limbing a spring pole- rich, felled, green Western Redcedar...flexible and long branches suspending the log off the ground. A bit of weight savings is helpful.