Note the textures, growth rates, and sensitive areas on your head/scalp/hair !
Pay attention to everything! From where you get the most buildup to how often you go between getting trims, especially as your hair gets mad long.
This kind of knowledge steps up your “growth game”, putting you in better shape to keep your length, as well as making you more aware of natural and unnatural changes and their resultant effects on your hair (i.e. diet, stress, product use/abuse, shedding etc.)
You know your body better than anyone else. Your hair should be no different.