Ken Norton: "my normal weight is 225-230 and i train down to 206"

To my understanding, optimal weight for an athlete is that weight at which they have the most pros and the least cons when it comes to their stats: strength, speed, stamina, coordination, reflexes, etc.

Some fighters can gain a lot of strength by putting on muscle, but lose out on speed. Some fighters become faster when they lose weight, but have stamina problems from the weight cut and/or can't retain hydration. Ideally, the goal isn't to approach it like a video game where you attempt to get 5/5 ratings in every stat (which is impossible anyways), but to get the highest stats possible at a weight that's comfortable for the athlete.

This is why it's not always good to constantly switch trainers, S&C coaches, doctors, cooks, etc. Sticking with the same team for an extended period of time has the benefit of the whole team knowing your habits, how your body reacts to certain things, picking up on your change in rhythm, timing, etc depending on your physical and mental condition as you gain or lose weight. I don't think these guys should be fired or released unless there's clear and present problems (too many disputes over money, theft, releasing compromising information, laziness, etc). They are the ones watching and observing your every day, every week, every month for potentially years and will notice many things you won't because you're focusing on simply training 90% of the time.