actually the old adage is:
one of sour
two of sweet
three of strong
four of weak

It's interesting that of all the bars suggested in this thread (thank you!), NOT ONE was among the five I visited on my last trip to Negril.
(I purposely didn't identify them because I didn't want to diss anybody)

So I have some good ideas for next reach, and will try to be more assertive in my requests to bartenders.