Why do loops differentiate between odd and even

[zhanggd112233]

The comment is to prevent deadlocks, but I don't understand

[ArturoSbr]

This is a pretty late reply, but I thought I could throw in my input anyway.

I think that may help in breaking the logical plan between iterations. I believe results are cached at the end of each iteration, so differentiating between odds and evens may help the interpreter understand that it should use the last cached result instead of going all the way back and building from scratch.