If I were to have a fully compliant cat6 or cat6a network running through my walls... that is to say, wires and jacks... What would be the concequence of plugging a cat5e wire into one of the jacks? I'm assuming that it would still run at cat5e standards, but obviously not cat6/6a standards because the whole connection is not cat6.

I only ask because it seems silly to me to make a bunch of cat6 patch cables for connections that don't really matter, like standard desktop computers and other equipment. Or will doing so hamper the whole network?