The plate mounts permanently, but the box can be released and taken with you. That's loosening the straps to release the hooks that hold the Yeti to the plate. So the question is how often would you want to take the PLATE with you, not the box?
FWIW, my experience in this has been that I made a custom Milwaukee Packout mount system for my bike because I frequently unclip and attach 2-3 different solutions to the top (
you can read about it here). That plate stays "permanently" attached to the bike, and the units that are clipped and unclipped come with me. I've been using this long term now and aside from potentially using a material that's too flexible for the mounting surface (ACB, would use a HDPE cutting board instead next time first), the solution has worked out really well.
If you do want to take the plate with you, keep in mind that you can buy an electric screwdriver nowadays for about $30, which makes the unscrewing out of the mounting holes problem much easier to deal with.