Why Britain preferred more medium carriers

Why would the Royal Navy prefer smaller carriers under a fixed treaty tonnage?

It needed six or seven hulls to cover multiple stations, so global presence mattered more than maximizing each individual carrier.

Britain calculated that it needed at least six and preferably seven carriers to meet its worldwide commitments. A treaty allowance supporting six 24,000-ton ships could be acceptable, whereas five larger 27,000-ton carriers left too few hulls for simultaneous presence. The smaller carrier might be individually less capable, but it was more useful than having no carrier on a distant station. When concentrated combat power was required, several medium carriers could operate together.