fcron tem segunda resolução para repetições
The entries of commands which have to be run once every m minutes of fcron's execution (which is normally the same as m minutes of system's execution) are of the form
@options frequency command
where frequency is a time value of the form valuemultiplier+valuemultiplier+...+value-in-minutes as "12h02" or "3w2d5h1". The first means "12 hours and 2 minutes of fcron execution" while the second means "3 weeks, 2 days, 5 hours and 1 minute of fcron execution". The only valid multipliers are:
Table 2-1. Valid time multipliers
meaning: multipliers:
months (4 weeks): m
weeks (7 days): w
days (24 hours): d
hours (60 minutes): h
seconds: s