Well, I know in the shows I watch, Ghosthunters, they film for roughly 8 hours a night. They arrive around 8 or 9 pm and leave around 3ish. It doesn't happen nearly as much as it shows on TV, but, it's like fishing, do you want to see an actual hour on the water where they don't catch anything, or do you just wanna see 7 hours worth of footage cut up with just the hour of good stuff.
Also, 8 times outta 10, you can figure out some other reason for what you hear. I rememeber I left an audio recorder in this cemetery and when I played it back, I heard what sounded like a gasp for air. It was weird, but, it wasn't concrete. On my next investigation at a mansion, I heard the same damn gasp when I listened to that tape. So, I concluded it was either a problem with the tape or the audio recorder.
Another time I went, I left a different audio recorder in an above ground burial building, ya know where they keep all the urns. A mosaleum, spelled completely wrong, lol. Anyways, I left it there, did a few laps around the cemetery with the camera, and when I listened to that tape, I heard CLEARLY, someone whisper/say "It's burning." Weird because obviously, it was a room full of "people" who were cremated. There was only 4 of us, and we stayed together, so it's not possible it was one of us, because it was inside, we couldn't get in cuz of a chain, we were just barely able to get our hand in a crack to set the recorder in there. And you hear all of us talking in the background, so you can clearly tell the difference between us and that womans voice. Sadly, I gave it to the chic I was with to upload it, and of course, she lost the tape.
So yeah, it doesn't happen nearly as many times as they portray it does, and I've certainly gone on more investigations where I didn't catch anything than ones where I did pick something up.
I'd love if you uploaded it so I can take a listen and run it through some software.