As a former projectionist, I have to say that while poor splicing and sloppy threading might be the culprits, the white screen of interruption is not necessarily due to your projectionist's laziness. Sometimes, snapped/melted film is the fault of the ancient projectors that the theater is too damn cheap to maintain properly. Sometimes it's the fault of the low quality prints that studios ship. Sometimes, it's the fault of the crappy splicing job of the projectionist in the theater that previously had the print.

Be kind to your local projectionist. He or she is running around in the dark like a caged rat attending to the needs of dozens of platters, splicing trailers and ads late into the night, building up and tearing down reels every Thursday morning until 4 AM, praying to the film gods for a week without a brain wrap or a power outage. Don't get me wrong, there are definitely more demanding jobs, and there's certainly no excuse for failing to check the focus and framing after the trailers finish, but some things are truly out of your projectionist's control.

But it's a Haiku, so you probably didn't have enough syllables to fully explore the complex, multilayered interplay between projectionists and their reels of film. I really think all movie lovers should follow around a projectionist for a couple days (preferably really bad days with really unreliable projectors) so they can fully appreciate the various crazy things that can cause those white screens. When you have a room full of spooling film, giant spinning platters, and light bulbs that burn with the heat of a thousand suns, wackiness occurs. Rube Goldbergian wackiness.

Hmmm.. it might be that they have cheap projectors since the theater is smaller, or it could actually just be a lazy projectionist. But you're right, a white screen should be extremely rare. Even back in my foolish youth when I watched 3 movies in a row every weekday (ahh.. college), I only saw one or two white screens a year.

I was a projectionist in a ratty, second-run art house theater, so most of the prints were already in bad shape by the time we got them. Our projectors were salvaged from a flooded theater in the south and then refurbished with whatever cheap parts the owner could scrape up, so my experiences probably aren't typical of the profession.