It makes no sense from a classical economics perspective to keep the theater empty. Even if no one is buying at the break-even price, it can make sense to sell below cost just to recoup some of the investment - and adjust the investment in the future, of course.

Now, in reality there are second-hand effects, of course - like people getting adjusted to the below-cost ticket prices and being even less incentivized to buy at the normal price.

Seems the same as a hotel - empty rooms benefit no one.

I guess it depends on who gets paid for the movie being shown, and who gets paid when a ticket is sold.

If it is free to show the movie then there is no penalty to running extra sessions. If it isn't free, someone is being paid. If that is a different someone to where ticket money goes they care more about sessions than viewings.