How many substrates are enough for robustness?

Also in this week's C&EN, a good article by Tien Nguyen about a "robustness screen" proposed by Frank Glorius: 

...Last month, researchers at the University of Münster proposed a screening tool that could help chemists figure out in a matter of days how well their reactions might work with functional groups on various substrates. Led by Frank Glorius, the team assembled a set of 15 commercially available additives that, when introduced to a new reaction, could tell chemists how well a sampling of functional groups responds to a particular reaction (J. Org. Chem. 2017, DOI: 10.1021/acs.joc.7b01139). 

Glorius readily admits that the additives approach, which builds on a “robustness” method reported earlier by his group (Nat. Chem. 2013, DOI: 10.1038/nchem.1669), simplistically tests functional groups rather than whole substrates. So it can’t tell chemists how the size, location, or electronic nature of the functional groups in the context of the entire molecule will affect a reaction, which is information typically provided by traditional substrate scope testing...

Interesting responses:

...Responding to C&EN’s poll, Eindhoven University of Technology’s Timothy Noël says it’s a good thing that standards are on the rise. However, he says, smaller research groups may suffer because they lack the resources needed to achieve the “monster” substrate tables now seen in elite journals. Noël’s group recently published a light-catalyzed decarboxylation method with 58 substrates (ACS Catal. 2017, DOI: 10.1021/acscatal.7b03019). The work was done by one graduate student and partly by a master’s student, which required a huge effort on their part, he says. 

Uttam Tambar, a synthetic chemist at the University of Texas Southwestern Medical Center, says the strategy for evaluating substrate scope seems to have changed over the past decade or so, since he was a graduate student. “The way we were taught is every substrate in your substrates table should teach you something about the reaction,” says Tambar, whose lab has also used Glorius’s robustness screen as a time-saving measure (Nature 2017, DOI: 10.1038/nature22805). “Now it’s almost become a numbers game. People want to shock and awe you with the quantity of the substrates rather than the quality of substrates.”...

 Gotta say, a list of "this reaction doesn't work with that" from the authors would also be helpful.