I would add 456-458, especially if activity is found within 451-453, though the 460s have been more common here in MA.
Typically I first hear a bit of activity on the Lighting/Electric channel during set-up a day or two in advance of filming. Then the transportation channels become very active the evening before filming or pre-dawn on the morning of as the production trucks roll into town and set up "base camp".
The very active channels (production, talkaround, camera, rigging, electric, transportation) can usually be found quickly. Lesser used channels take some work. In some productions, a production assistant will "spin the channels" and make very brief announcements on all 16 channels at the beginning of filming ("we're in"), for the last shot of the day ("martini"), at the end of filming ("that's a wrap"), for lunch breaks, and so on. I've identified many otherwise unused channels by anticipating these announcements and watching the staircase effect they generate in SDRSharp's spectrum waterfall, and using the timeshift or the spectrum recording option to play back the transmissions after they've all ended to snag both PL and frequency. The spread of known frequencies can provide clues as to where to look for the unknown ones.
None of my filming loggings have been digital. Directors sometimes give vocal instruction with their mics keyed so they are heard both out loud and over the air. The echo effect caused by the encoding/decoding delay of digital modes would make this problematic. During production, camera crews, electricians, and riggers often whisper into their radios or speak very softly while on the set so as not to interfere with filming. This too would be challenging for digital vocoders. And quick transmissions are sometimes more rapid-fire than would be possible with digital modes.
If you're confused by what you hear, there's plenty of info online about the various movie production roles, walkie-talkie lingo & etiquette, etc.