Aluminum plate joist installation - attach both sides?

SteamtoHotWater

I've got a few hundred extruded aluminum plates that I'm installing. I bought Uponor Joist Trak. Install seems simple enough, "Install the Joist Trak panels with either screws or nails into the pre- punched mounting holes."
However, a different brand of extruded aluminum plates, Watts, suggests, "Now attach one side of the plate with four 1⁄2" screws as shown and let the other side "hang". Do not install screws on both sides of the plates - this will allow the plate to expand."
Both brands of plates looks pretty similar, same size, same kind of channel for the pex. Should I be attaching these plates on both sides or just one side to allow for expansion?

Alan (California Radiant) Forbes

We've always attached them to both sides for better contact and heat transfer. There will be some expansion noise; less if you have outdoor reset.

kcopp

If they are the "good" aluminum plates attach both sides... If they are the thinner "beer can" plates then just one side. That is prob what the post you saw was.
I do agree about the expansion noise.