When I teach Rule 1.2(a), I always ask why there needs to be a rule that clients get the final word on settlements. Why not allow freedom of contract to have its way? I don't know that there is a satisfactory answer to the usual preference for free contracting (subject to duress defenses, etc.), but I find it useful to use the rule to explore client-lawyer conflicts that might arise from differing tolerances for risk.
The simple story centers on contingent fees and diversification. Plaintiffs' lawyers who have a portfolio of non-identical cases might rationally be willing to turn down a lowball settlement offer in the hope of a big verdict (or higher offer closer to verdict) than would be the plaintiff, who has only the one case. Different risk tolerances would create a reason to expect conflict in contingent-fee cases, and the rule goes some way toward ameliorating that conflict.
But is the simple story true? I imagine there would be little if any hard data on the frequency of such conflicts (the privilege would impede data-gathering). Does anyone know of any effort to estimate how often such conflicts arise?