How soon can MMF be used once you make a batch of it up? Does it need to be refridgeratored or is it okay to sit out???

Hi there. I'm sure you'll get better answers from others who have used it more than me. When I made my first batches of MMF a few months ago, I made the recipe and let it sit overnight before using it on my cakes. I wrapped it well, then put it in a zip lock bag, then in a sealed plastic container (although some might say that's a bit overkill). Mine sat out on the counter in a dry room-temperature area.

The recipe I've been following says to let it rest for 1 hour after making it, but I haven't found an explanation on why.

I wrap mine in plastic wrap, then stick it in a plastic zip lock bag. I don't put them in the fridge. I think it's good for a few weeks?

I did a quick internet search and most hits report that they let the batch rest overnight. Anyone know why?