If anything they should open up SE sales a bit before LE sales, because I highly doubt that people are going to have to worry about if they can get an SE or not.
Yea, I think they should sometimes stagger sales because if people are gonna be losing out during checkout, then it's not wise for people to go back and forth adding them up in the cart to combine orders. I usually just try to grab one and check out and then go back for the other ones I want. I end up paying more for shipping as a result.