This is probably a stupid question but I thought I'd run it by you experts anyway!
Is there any reason why you couldn't fill multiple molds at one 'sitting'? I mean, assuming you're willing to use the same chocolate could you fill - i.e to create the initial outer shell - scores of different molds in one go? Then you could just reach for them as and when you need them, which presumably could save some time and effort further down the line. Surely better to blitz the issue in one big go than do the odd few molds here and there? You could store the molds as you would empty ones, perhaps with some parchment paper in between. There would be no shelf life questions as it's only chocolate (so no water activity issues) and if stored correctly I can't see why you couldn't do it and then not have to mold (beyond backing them when needed) for months.
There's no reason at all you can't do this. I make lots of molds at once, use what I need and store the rest for later. You need to make sure to keep the filled molds cool and dry, keep pests/rodents out as well as dust. I will often loosely wrap them in plastic wrap once they are totally cooled and set. I store them in a cool dark room (that was intended as a wine storage area). I've never had an issue using a mold like this at a later date.
BTW, there are no stupid questions here. We all started at the beginning of the learning process with chocolate. It just nice to have a place to go to seek answers.
I've done it a lot. If I'm working with one type of chocolate (milk or white especially, since I don't run those as much), I'll try to get as many molds lined as possible. After they have set, I wrap each one in plastic wrap to keep out dust, and store them in bins I use for the molds. I've had no trouble with them at all. And, I don't have a problem backing the dark chocolate with milk or vice versa. It saves time and who's gonna notice a thin layer on the bottom?