No one is saying anyone “has to” do anything to their heads.
But some want to have them be better than they come ootb.
This is how they get a feel for what to do, how long it takes, and what you can expect for results for the effort....... or if you’re not inclined to do it yourself.....what you’d get beck from a shop that you had do it for you.
When I do this type of small clean-up job I don’t usually bother testing them ootb.
They get the whole job done, then I test one pair of ports, and iiwii.
I test them ootb when it’s something I haven’t had in the shop before, to see what they flow like, so I can gauge how effective the rework is.