Would the odd times not suggest that
a - she is not rushing people out the door
b - she is taking 10-15 minutes to clean up.
If everything is bang on the hour or 30 minutes then either
a - she is starting punts a minute late and finishing a minute early to give herself a 2 min wipe
b - she is taking 30 -60 minutes between punts to freshen up - possible for some but unlikely for others
Think odd times may be safer bet