I would have thought that someone must have asked this already but apparently not.
The ordering of the Stack Exchange drop-down menu is at times [in parts] logical, and then there are random positionings. Take a look at this:
This answer to the question Why is the list of all sites in the Stack Exchange dropdown not sorted?, does not explain the ordering that I see:
Sites where you have > 200 reputation will be sorted by reputation, highest reputation accounts at the top.
Sites where you have < 200 reputation will then be listed in random order. e at the top.
It is not because I need to wait 24 hours either, as it has been like this for nearly a week. In fact, it has always been badly ordered - only now am I analysing the order, or trying to.
3D Printing messes up the ordering at the top of the list - is this because I have always been on that site, in the past few weeks, and so it has been positioned as a favourite?
Surely Ask Ubuntu should be just below Stack Overflow, and Arqade at the bottom?
If I scroll down that menu, it gets even more random, and not all of them are < 200, so the explanation in the answer above, doesn't appear to apply: