I think Brian did a very good job of summarizing some of the differences between the two approaches. You can think of NCA (most often used in early phase) as an approach used when we know little about the drug and want to generate some basic quick descriptors of the nature of the kinetics of the drug.
In a very basic sense all I need to perform NCA is dose amount, time from dose, and concentration of a serial set of samples. So an NCA dataset can be pretty basic. As Brian pointed out we often use patient characteristics to at the very least summarize the basic parameters we calculate, so the dataset can grow in complexity as the needs do. The results from NCA are dose event based (i.e., the resultant parameters from a single dose event or a steady state dose event are single point representations) so linking that AUC/exposure estimate to some sort of continuous time based covariate is difficult and usually not a requirement.
That does not mean that we could not want a dataset with time based covariate type linkages, because an underlying overall project goal might be to combine several single study datasets to generate a meta study early population based analysis.
Brian also mentions the use of urine data in NCA, we may use total amount excreted (derived from the urine data) in a population based dataset, but it would be a rare compound and a rare need where we would feel it necessary to try and model urine data with population methodology.
I hear the underlying message behind your post, and I infer that to mean, “do I have the ability to push back on what I perceive as requests for an overly complex dataset that is supposedly only going to be used for NCA analysis” The answer would depend on what the scientist wanted to do with the data overall. Maybe NCA is the primary goal, but off the main developmental chain, the request for the more complex information is intended to support early phase model development which then would necessitate a more complex dataset. I think it is completely fair to have the conversation with the scientist to determine if the level of complexity is warranted.
Finally, Brian is correct in his mention that the dataset constraints are much more rigid for the population based analysis programs than they are for the NCA programs. So while standards can come into play for both, there will be more extensive sets of “rules” for a population based dataset than an NCA one.
Is that where you were wanting to go with the discussion or did I miss the mark?