Allow me to add one more point I realized while proofreading my post.
According to the N shysters, only O leaks out, so when our average tire above leaks again it is only possible to leak 5% of its contents. call it a 5% loss of 50# pressure to 47.5# which hardly anyone can notice. Meaning you probably never have to refill again. Or once more at most. IF the shysters are right about N not leaking. And that's not what happens in the real world.