To keep the batteries longer - do not run them completely down before charging. It is preferable to keep batteries fully charged all the time.
If after the short use - you do not plan to use the cart for a long time - it is better to recharge; if you will continue to use it - no additional charge needed.
Any recommendations are base on of estimated use - if you use one hour - the recommended charge time is two hours.
As a rule of thumb - the charge time is:
-- 6 - 8 hours after 18 holes of golf
-- 4 - 6 hours after 9 holes.
To charge the battery every time it was used - that is a rule of thumb we should follow.
To keep the batteries longer - it is preferable to keep batteries fully charged all the time.