plan
籌 centers on planning and calculation, originally tied to counting sticks or tallies used for strategizing.
籌 combines 竹 (bamboo) with 壽, which likely provides the sound. Historically, bamboo tallies were used for counting and planning, giving the character its meaning.
Bamboo 竹 over 壽: imagine ancient planners using bamboo counting sticks to devise strategies, with the lower part suggesting a long, thoughtful process.
For チュウ, picture a planner chewing on a bamboo stick while thinking: chew -> チュウ, tying the sound to the act of planning.