Despite differences in objectives and tasks, I wonder how one can reconcile the present theoretical approach with the recent results presented in the following:

Granatosky, M. C., Bryce, C. M., Hanna, J., Fitzsimons, A., Laird, M. F., Stilson, K., ... & Ross, C. F. (2018). Inter-stride variability triggers gait transitions in mammals and birds. Proceedings of the Royal Society B, 285(1893), 20181766.

The critical slowing down and fluctuations found when changing gaits in several species indicate a phase transition. One would desire a unique theoretical framework to account for permanent and transient gait. Optimality and self-organized patterns are likely two sides of the same coin, like Benard's hexagonal cells in a (viscuous) fluid heated from below are optimal to dissipate heat and at the same time self-organized patterns. Julien Lagarde