As of January 1st, 2019: Ring gates may now be closed and a qualifying run may still be earned. This is a club level decision on whether they will have ring fencing that accommodates this option. Most clubs will continue to have open fencing where this is not an option.
This does not negate the fact that dogs must still enter the ring in a timely manner. A dog waiting outside the ring gates for the dog ahead of them to finish will still be considered a delay of trial and faulted accordingly to the severity of the action.
If a handler wishes for the gates to be closed, and for the next dog to not enter until their dog is leashed then this will be considered a training run and an E will be given.