I was just talking with someone about this the other day.
The idea of supervision makes more sense for some pairs than for others. It makes perfect sense why an SLE would be harshly critical of an LII, or an ESE of an SLI, but for LII and IEE? I have "hit the PoLR" of IEEs before but mostly we get along great. IEEs tend to get along well with most people anyways.