A properly controlled GF will have hydration stations at reasonable intervals to replenish H2O unlike self-supported LD rides where it's catch-as-catch-can. Being prepared for the actual time/distance between service opportunities is all that is necessary in an organized GF event. Find out from the organizer how the on-route service is provided, if at all and plan accordingly. That being said time spent in a service stop in a timed event produces Zero distance covered with the clock still running. Managing service stops to an absolute minimum time or eliminating them entirely avoids zero Mph, missing water when needed results in a DNF.

-Bandera