As a boat/shore guide in a visitor destination, I'm pretty sure I can speak for my peers about the most likely regulator on the boat to free-flow; the serviced last week previously in some landlocked closet for the last 18 months reg. Even my oldest and ugliest rental reg was in the water just a few days ago and worked well enough to make a dive. 
Percentage of dives aborted due rental reg failure vs successful rental reg dives might be less than 5%. Percentage of dives aborted due occasionally used personal reg failure vs successful occasionally used personal reg dives might be over 30%.
95%. Percentage of tourist divers who had to abort first vacation dive due occasionally used personal reg failure who said, "I just got that reg serviced before I left home."

Percentage of dives aborted due rental reg failure vs successful rental reg dives might be less than 5%. Percentage of dives aborted due occasionally used personal reg failure vs successful occasionally used personal reg dives might be over 30%.

95%. Percentage of tourist divers who had to abort first vacation dive due occasionally used personal reg failure who said, "I just got that reg serviced before I left home."
