As noted elsewhere, one Response before Final is too short. Why have a limit? Compact prosecution is a false goal if it results in useless patents. And the current RCE practice assumes that no prosecution needs more than one Reponse if the attorney is being "reasonable;" when in fact a "reasonable" attorney (working with a reasonable examiner) may need different numbers of responses in different cases.
Why not substitute a progressively increasing fee for each response after the first. Unreasonably demanding attorneys will be curtailed because at some point the cost of the next response will outweigh the likely benefit to the applicant. This would also flexibly accomodate many potential prosecution trajectories, without lumping them all together as "never requiring more than X responses."
It would also provide additional benefits, such as useful statistics on how many responses really are needed in various art units, identifying outlier Examiners or prosecuting attorneys, without the skew introduced by the arbitrary RCE deadline. In time, it may become clear that very few cases are really ready for disposition before the third Response (for example), or that very few cases really need a third Response (for example). In a sense it is a market-based approach to compact prosecution.