I know something about complex control systems (MPC implementations). There's a lot of trial and error involved. Breaking the task down into small composable ta

I know something about complex control systems (MPC implementations). There's a lot of trial and error involved. Breaking the task down into small composable tasks is definitely helpful. There are definitely many tight feedback loops that are necessary, whether they are 2 weeks or longer. Things get tweaked all the time, especially in production. There's stuff that don't show up in testing, and there's cases that cannot be anticipated. There's definitely some control analysis to identify default tuning parameters, but the proof of the pudding is in the eating. The design tuning parameters are only initial values -- they are tweaked online while the plant runs. There's an upfront spec but that spec only provides guidance. The real world will often surprise you. There are elements of waterfall at play, but the entire process by necessity cannot be waterfall.