The whole thing with switching rackets is interesting.
I have had partners who have four different sticks in their bag. They spend the whole match switching rackets or bouncing the strings off their palms, attributing poor play to needing to string the racket or just having had the racket strung. Then they will yank a completely different frame out of the bag and proceed to express frustration at that one.
Me, I like to have two identical frames with identical strings and identical tensions. That way, I can focus like a laser on the real reason I lose: No footwork.
-- Random Error Generator, Version 4.0
-- Master Moonballer