Sure Greys are baby yellows, but like asparagus, the young tender shoots are tastier! As the soil warms grey pops are isolated to the cooler microclimates then it's the yellows only. I'm done when I get enough for me and friends and leave the late season big and fast turning rusty ones to repopulate or those who want them because I think the flavor is lessened.
We all have our theories even if science- based. I prefer thick outer bumpy and thin inner smooth of early to late mid season over the thicker inner smooth of and thinner outer bumpy part of late season morels so I stop when I get 60#_ 75# each year. I know how to find, pick, and the basic science so I really just skip past the advanced arguments about why shared observations, technical terms, and descriptions of finds are scientifically wrong. I like others findings and take it for what it's worth.
Good pickings and don't litter- please pack out your trash