Four colours is the practical ceiling

The limit is human, not technical

We can produce as many colours as a property wants. What we cannot change is that staff distinguish about four reliably, at working distance, while doing something else, under evening light, against wet skin. The fifth and sixth get confused. The moment a member of staff is publicly wrong once, they stop relying on the system entirely, and a colour scheme nobody trusts is worse than no colour scheme at all because it looked like a control.

Most properties do not need as many as they think

A property with seven package levels usually finds, when the exercise is actually done, that a server adjudicates two or three things — whether a drink is included, whether a restaurant is included, whether a child pays. The other four distinctions concern room category and transfers, which nobody at a bar ever assesses. Those belong in the reservation system, and moving them there is free.

Test contrast where the band will be seen

Colours chosen from a swatch under office lighting are chosen against the wrong background. The band will be seen against wet skin, blue water, white towels and whatever colour the buoyancy aids are. A blue non-swimmer marker against a blue vest in a blue pool is invisible at the distance a lifeguard actually works from. Ten minutes on the deck with candidate bands settles this before a season is committed.

Never reuse a colour

If red means non-swimmer this year and top-tier package next year, every member of staff trained on the first meaning is now a hazard. Keep a written colour register: one colour, one meaning, indefinitely, with colours reserved for events and groups so a conference band can never be mistaken for a guest tier. It costs nothing and it is the difference between a system and a habit.