I don't know if that's actually a useful reference class for analysis
I don't know, either, but I feel that some research in this direction would be justified, given the potential payoff.
The other has to do with perceptual thresholds and just-notic[e]able differences.
This might, in fact, be one of the models: the metric being observed hides the "true growth curve". So a useful analysis, assuming it generalizes, would point to a more sensitive metric.
Related to: What Do We Mean By "Rationality?"
Rationality has many facets, both relatively simple and quite complex. As a result, it can often be hard to determine what aspects of rationality you should or shouldn't stress.
An extremely basic and abstract model of how rationality works might look a little something like this: