Why a multi-round treaty process?

[Today's actual post!]

There seems to be a general attitude in large-scale environmental negotiations that the right way to approach them is to try to get lots of people to sign on to relatively light requirements, and then hold multiple subsequent rounds of negotiation in which you slowly ratchet things up. This is actually sort of an intuitively satisfying model, I think - I mean, it seems like how you might intuitively approach a hard issue - but I've had oddly little luck finding scholarly discussion of treaty-making that discusses this attitude explicitly or breaks it down into an actual theoretical process. I'm sure it must be out there, because the attitude definitely exists and someone must have tried to fit a theory or theories to it, but I haven't yet been able to find them. I've thought of three possible ones, though:

1) Best diplomatic practice: one could postulate that the best (or even, only practical) way to get large concessions is to stair-step toward them: secure one set of small concessions at a time, using each as the new baseline from which to launch a renewed negotiation.

2) Harnessing learning effects: one could postulate that one can, at any given time, only get people to commit to relatively small expenditures; however, each execution of each commitment causes learning, which reduces costs and ambiguities, freeing up resources for another round of commitments. Hence, negotiation should be built to encourage and accommodate that process.

3) Normative spiral: Risse, Ropp, and Sikkink have proposed a "spiral model" for uptake of norms such as human rights at the state level, which could also apply here. Without going into it in detail, basically the model postulates that uncooperative states can be pressured into making small tactical concessions. Although these concessions are initially viewed as onerous and externally imposed, after a period of adjustment and acculturation, the state takes them up as its own norms and begins to behave in manner consistent with the concessions, viewing the new regimen as part of its normal behavior and identity; this in turn makes it more open to taking further steps. In other words, a spiral in which initial concessions change states, creating space for further concessions, and so on. If we view environmental treaties as promulgating norms of environmental behavior, we can imagine this spiral process occuring through the treaty process, with each round consolidating and building on the effects of the prior round.

But I haven't actually found an instance yet of any these explanations (or others) being mobilized to provide a formal theoretical underpinning for actual observed practice. Surely they must be, and I just haven't found it.