If asked to pick the top two good things that I discovered about grant review when I first went for a study section stint, I'd have an easy time. The funny thing is that they come from two diametrically opposed directions.
The first amazing good thing about study section is the degree to which three reviewers of differing subdiscipline backgrounds, scientific preferences and orientations agree. Especially in your first few study section meetings there is little that is quite as nerve-wracking as submitting your initial scores and waiting to see if the other two reviewers agreed with you. This is especially the case when you are in the extreme good or bad end of the scoring distribution.
What I usually found was that there was an amazingly good amount of agreement on overall impact / priority score. Even when the apparent sticking points / points of approbation were different across all three reviewers.
I think this is a strong endorsement that the system works.
The second GoodThing I experienced in my initial service on a study section was the fact that anyone could call a grant up off the triage pile for discussion. This seemed to happen very frequently, again in my initial experiences, when there were significantly different scores. In today's scoring parlance, think if one or two reviewers were giving 1s and 2s and the other reviewer was giving a 5. Or vice versa. The point being to consider the cases where some reviewers are voting a triage score and some are voting a "clearly we need to discuss this" score. In the past, these were almost always called up for discussion. Didn't matter if the "good" scores were 2 to 1 or 1 to 2.
Now admittedly I have no CSR-wide statistics. It could very well be that what I experienced was unique to a given study section's culture or was driven by an SRO who really wanted widely disparate scores to be resolved.
My perception is that this no longer happens as often and I think I know why. Naturally, the narrowing paylines may make reviewers simply not care so much. Triage or a 50 score..or even a 40 score. Who cares? Not even close to the payline so let's not waste time, eh? But there is a structural issue of review that has squelched the discussion of disparate preliminary-score proposals.
For some time now, grants have been reviewed in the order of priority score. With the best-scoring ones being take up for discussion first. In prior years, the review order was more randomized with respect to the initial scores. My understanding was the proposals were grouped roughly by the POs who were assigned to them so that the PO visits to the study section could be as efficient as possible.
My thinking is that when an application was to be called up for review in some random review position throughout the 2-day meeting, people were more likely to do so. Now, when you are knowingly saying "gee, let's tack on a 30-40 min discussion to the end of day 2 when everyone is eager to make an earlier flight home to see their kids"...well, I think there is less willingness to resolve scoring disparity.
I'll note that this change came along with the insertion of individual criterion scores into the summary statement. This permitted applicants to better identify when reviewers disagreed in a significant way. I mean sure, you could always infer differences of opinion from the comments without a number attached but this makes it more salient to the applicant.
Ultimately the reasons for the change don't really matter.
I still think it a worsening of the system of NIH grant review if the willingness of review panels to resolve significant differences of opinion has been reduced.