I'm familiar with this custom. Unfortunately, I've adopted the habit of not leaving voicemail (if I'm determined, I talk gibberish until the callee picks up).
And I haven't listened to recorded VMs for years. Way back when, I actually bought a machine for answering phone-calls. I have no idea what I was thinking :-)
Voicemail transcription is the only reason the "ignore it and if it matters they'll leave a voicemail" strategy works for me. I never, ever checked voicemails back when I had to actually listen to them. Now I can skim ten of them in a few seconds to see if any were legit. Most scammers/spammers don't leave a message anyway, so the volume's pretty low.
And I haven't listened to recorded VMs for years. Way back when, I actually bought a machine for answering phone-calls. I have no idea what I was thinking :-)