Why should it make a difference ?
Thinking, and can not see why...
That does not mean it is not correct though.
In my mind (NOT experience), it would not make any difference whatsoever.
But would like to hear why it should ?
I never ever close the valves - and have removed the valves on some of the big kitesizes, and they are way faster and easier to pack down.
Havent removed them in the small sizes, because they are fast to pack down anyways, AND for the occasional use when out in rainy weather, and I pack the kite halfways down with struts inflated - so I can keep it from getting "ugly" and mouldy/colour smeared, by drying it back home standing on the struts
Still, I never close the valves when on the water - so only used the rare times the kite is rain wet when going ashore and packing down.