Read hair and scalp the way a botanist reads a field: by need, by season, by origin.
By need
Oily at the root and dry at the ends is not one problem but two. Treat the scalp and the lengths as different terrain and the routine gets simpler, not harder.
By origin
Match the botanical to the need: green tea to balance, caffeine to strengthen, bamboo to moisturise, camellia to calm. Origin is not romance; it is the reason the ingredient works.