The only time I have observed strict 'go' times enforced is when there are several performances for the venue one after the other, such as college and high school competitions and festivals.  You can't hold the curtain when there is such a tight schedule, or when campers have to be back to camp by a particular time. 

 

When to hold the curtain-

 

Weather often plays a part in this-  we generally watch the traffic carefully when there is rain or snow or ice. If people are making the effort to get to the show, then we'll make sure they see the whole show! 

 

When you have outdoor venues, you may or may not have delays based on weather.  The Santa Fe Opera used to be completely open air, and If it looked like rain, you were warned if you were sitting where you had a good chance of getting wet.  If the Opera happened to be on a unit set (very rare), the show would go on with no delays.  If there was rain on a multi-set show, then the stage crew had lots of fun trying to keep the sets dry going from the stage to the storage areas and back, and intermissions generally ran much longer than the preferred 20 minute break.  (we cheered the night we got a monster set change done in under 20 minutes for the first time in the season- then had to shush immediately, of course)

LIGHTNING will shut down all outdoor performances until the storm has passed (or at least chase the followspots out of their perches)

 

We have had to hold curtain for technical reasons, and of course it's never an actor who is late, they're late because of a 'technical' problem (when they should have been in costume earlier than 10 minutes before curtain to figure out that jumping around would blow a shoelace). 

 

The one with a parking lot we nearly always start on time or within four minutes of on time dependent on the stage and house managers.

 

The theatre without a parking lot, curtain is nearly always 10 minutes late and it is because of parking issues.  Of course, the patrons running the latest get the parking furthest away, which makes them even later arriving. 

 

It is far too disrupting seating patrons after curtain. We "cover" by having a curtain speech at curtain time.  I'm not a big fan of curtain speeches, but it has been well accepted. We use it as an update of activities, a form of marketing, and occasionally a "shout-out" for special reasons like a wedding anniversary of someone in attendance, but mostly it is so we can seat late-comers.

 

We recently held the curtain for an intermission because we refused to rush one of the patrons who was chatting with playhouse members at intermission.  (She had recently single handedly paid for our renovation.  That's worth five minutes of curtain holding to me)

As a generally observation, I think audiences have picked up bad habits from the local movie cineplex, where they decide to wait in line to get a barrel of popcorn because they know that there will be 5 or 10 minutes of movie trailers...plus more often lately...commercials!  So they bring that bad habit with them to the fine arts theatre.

 

We have never started "on time" at my educational theatre.  We generally hold the curtain for 5 minutes after the posted show time.  This is an artistic choice on our part, because we don't want two dozen latecomers letting light shine in or banging the doors during the exposition scenes.

 

Sometimes we will do a pre-show announcement on the "God mic" telling people to silence their phones and not to use flash or video.