Not sure what you mean by "true ordering windows" If you mean like the ones that OSK has on his site where typically (but not always) an item disappears after the stated ordering window then yes, I agree, they don't have an ordering window like that.They usually don’t have true ordering windows. Their old website showed how many pieces of a certain item were in stock. They updated their site recently though and now the stock count doesn’t show. Maybe this is something new they’re doing?
BUT, they also don't have infinite open orders up until the figure is released as they do have an ordering window with Sideshow to secure their total allotment for their store (# of Pre-Orders + a few extras).
Their email newsletters always say when the ordering window was closing (this being in reference to AEC's ordering window with Sideshow), so this isn't something new they're doing. For example, their ordering window with Sideshow closed months ago for HT AOTC R2D2 and the figure was shown as "sold out" on their website. Then, I checked about 3 weeks ago and the site showed "1 in-stock" which more than likely means someone canceled their order. I ordered it, and after about a day or so, the item went back to "sold out."
The only difference here is that Sideshow has told AEC that the ordering window with them for THIS specific figure is only 4 days long vs the usual I think month they typically have to secure their allotment. AEC will probably still order a few extra on top of the POs they get, though; but now, due to the new website, you won't be able to look at the item page and say "oh I still have time, they have 10 left." So, like any other HT item they offer, if you want to guarantee your order with them, then you need to be sure to order before the window closes.