The gigbags for accordions that are intended to be stored in the playing orientation actually come with strap lugs to carry the bad in the playing orientation (not all of them) and when you put the accordion in the bag down in the playing orientation they zip open in such a way that you can pull the accordion up from the bag in that orientation and put it back that way too.
When an accordion is in the playing orientation all the valves are horizontal when you consider their length and vertical when you consider their width. So gravity does not pull the valves open or closed.
When you place a (LM) cassotto accordion in its feet then gravity pulls on the outside valves of the L reeds and on the inside valves of the M reeds. Fixing sagging valves for the L reeds is easy. The valves for the M reeds cannot be fixed without either removing the reed plate or the valves (which is a delicate job with tweezers).
When an accordion is in the playing orientation all the valves are horizontal when you consider their length and vertical when you consider their width. So gravity does not pull the valves open or closed.
When you place a (LM) cassotto accordion in its feet then gravity pulls on the outside valves of the L reeds and on the inside valves of the M reeds. Fixing sagging valves for the L reeds is easy. The valves for the M reeds cannot be fixed without either removing the reed plate or the valves (which is a delicate job with tweezers).