You thouched the core of the thing at the very end: basically how appropriate or not it is to ride in center lane when there’s plenty of room in the rightmost lane depends on how frequent exits and entrances are in the stretch of road you’re in as well as how those entrances and exits are setup (basically, how long is the merge lane), the speed you’re going at and the risk due to things on the side of the road.

I don’t think anybody is contesting not being on the right lane all the time in an avenue in the middle of a city where there are constant junctions with side streets.

That said your “cognitive load” theory is all about doing what’s best for yourself and fuck everybody else - if somebody is needlessly on the center lane when there’s plenty of room on the right lane and plenty of distance between entrances, then they’re just needlesslesy forcing others to endanger themselves by going into an even more dangerous lane, and doing because they lazy and selfish (because having to pay attention maybe once every couple of minutes to entrances or overtaking isn’t all that much cognitive load unless one is an actual moron in the scientific sense.

That’s the same logic used by people who don’t use direction indicators unless it’s helpful for them personally.

The optimal level of selfishness so that the road is as safe as possible for everybody is quite a bit below “whatever is less of a hassle for me”.