Amazon Shipping Oddity

I ordered three items from Amazon today... all small items. One of the things that Amazon's added recently (well, a year or two ago) is the concept of "Add-on Items." This is for things that are not profitable to ship with Prime but we still want to be able to offer these items to customers.No problem. Figure that if I orders items today  I should be getting these on Tuesday, right?Well, I guess Amazon over-delivers. Oddly.I'm getting the two add-on items on Sunday and the non-add-on item on Tuesday.This just seems like a fail. No, I'm not complaining about getting things sooner, but if the idea was to save on shipping, it's an odd strategy to ship the two things that are "add-ons" apart from the main item.Go figure. I'm sure someone is working on it.