wait_seconds in pg_ctl

Hi,

I would like to know is the wait_seconds inside the pg_ctl script changable?
If not, do you know what would happen if someone changed it from 60 sec to 7
sec?  I found that my configuration has been changed by someone else in
order to shorten the shutdown wait time.  But I am guessing there is some
fundamental reasoning for the default values (60sec) and would like to know
what's the side effect if this has been modified.

Thanks,

--muteki