I would have to hunt down any specific reference, so no there is nothing I could list right off the top of my head. The ideal load-recover-supercompensation allows a certain improvement slope. One can only load stress to a certain point, beyond which is the territory of overtraining (aka underrecovering). To map out how – as opposed to the typical pattern of load one day and then recover for one or two days before loading again – a graphic representation of loading for two days and then recovering for three or more days might look, it would likely yield a flatter overall slope. In other words, it would seem that one could see greater gains by fitting in two 2-3 day cycles instead of one 4-6 day cycle. It strikes me as being an unnecessary compromise. Otherwise the best of the best would be known to train like that.