Don't know why it took me 65 years to figure this one out.

Windshield wipers at rest develop a 'set' to the blade. This, after
time, causes the wipers to skip, hop, and squeak as they go across the
windshield.

When this happens, simply remove the blade from the wiper housing,
turn it end for end, and reinsert it into the housing. Works like a
champ. You'll think you bought new blades, or at least my wife did.
--
John H

All decisions, even those of liberals, are the result of binary thinking.