For the record, I predicted W and X.Qon wrote: ↑Fri Jun 07, 2019 9:24 pmGood joke!
No one managed to predict what U, V, W & X would look like. People constantly come up with wrong rules even for cases that they can check against the examples posted in the thread. It seems to be impossible to predict what will happen. You would have failed too if you didn't have the images to check before you posted.
And yeah, csduff's "If curved, place in the lane that is more often farthest from the inserter" covers what I was attempting to get at fairly well (by the concept of the "far" lane, even in the first post, although at that point I simply generalized that concept as how it appeared in the examples given).
One thing to consider is that U and V, and W and X, are rarely used in real designs (which is used less is debatable), so even those who are familiar with inserter mechanics have little to no past experience with those configurations, and as such have no prior knowledge to use to base these patterns off of. People can predict the mechanics for the belt configurations they regularly use; if these "odd" configurations were used more often, it is likely that some people would have predicted them without the images being posted.
(also, posting 20 belt configurations does carry a bit of the implication that that is all of the possible configurations that need to be tested against.)