It's an old chestnut as they say, although in my campaigns a jump regardless of distance always cost the full fuel cost, hence ships have to refuel after every jump. I used to allow multiple jumps in my old MT campaign, but decided not to after reading the T20 rules (based on classic traveller) that seem to imply that all jump fuel is used per jump regardless of distance travelled. One thing is definate though, jumps of any distance always take roughly one week (6-8 days, the average of 7). In a typical star system, there will be many in system destinations that even with a good m-drive will still take over a week to get to, hence using a 'micro-jump' in a fairly slow ship/vessel such as a merchant (1 or 2 G typical accelleration) can give you a considerable reduction in travel time, particularly in very large binary or trinary systems.
Hope this helps.
