I try to get 2 of everything that way I can open one and leave one MOC. The only ones I don't open are the truly rare ones that I was lucky enough to get period like Playmates' Star Trek 1701 Picard figure or Yesterday's Enterprise Yar. When I was a kid though I opened all of them but surprisingly all my childhood toys(GI Joe, Transformers, He-Man, She-Ra, M.A.S.K., Super Powers, Thundercats, Star Trek)--which I've managed to still have 2 decades later--are about as in good a condition as they originally were.
Since Star Trek toys seem to be fading though in terms of releases I've only been collecting the nostalgic toy lines Mattel has resurrected that I collected as a kid -- the brilliant DC Universe Classics and Masters of the Univers classics--those I get two of each--one to open and one MOC plus additional ones when they come with multiple heads you can switch out.
Since Star Trek toys seem to be fading though in terms of releases I've only been collecting the nostalgic toy lines Mattel has resurrected that I collected as a kid -- the brilliant DC Universe Classics and Masters of the Univers classics--those I get two of each--one to open and one MOC plus additional ones when they come with multiple heads you can switch out.