1. No. You do not start the movie a few minutes before the schedule.
2. And you most certainly don't imagine that a lady with a struggling kid on one hand and a bag of kiddy stuff on the other arm does not deserve to be escorted to her seat with a flashlight to prevent kid and lady from almost stumbling over the uneven floor.
3. Intermission does not mean that the screen should go blank without warning probably when the actor is in mid-sentence. Someone like the lady in (2) above will imagine that the current supply has ditched.
4. Intermission duration cannot so long that you need to take several rounds of snacks to fill the time or so short that you hardly walk out from the theatre that you need to stumble back in the darkness.
5. There is something called the right volume.
6. There is something called right level of aircon. Don't imagine if you start with frigid levels of cooling and suddenly switch off the aircon, nobody will notice because they will be too engrossed in the movie.