I thought that DocSpock liked his rum in rather large quantities but some of the figures quoted above suggest that there's either confusion over metric units or else that there are some very heavy drinkers around here!
A bottle of rum holds 700ml (70cl). A standard pub single measure always used to be 25ml (but the option to serve in multiples of 35ml was later introduced as well). So Pasta is putting 4 small measures of rums into the recipe, and Howard is putting 8 to 10 tots (around a third of a bottle) in!
Most people probably wouldn't put more than a 'double'(50ml) into such a recipe, with many people only using a 'single' (25ml). So I agree with Annadomino.
Chris