Dad would gleefully find one in the mail, unwrap it, open a beer, and sit down with his headphones on and notepad in hand. Once in a while he'd actually pause the playback while jotting notes, but mostly the things he wanted to respond to only needed a scribbled word or two as a prompt for later.
Having finished the tape, he'd walk around for a minute to collect his thoughts, grab a second beer but not open it, rewind the tape, press Record, wait a count of 5 for the leader to be past the record head, then crack that beer right into the microphone -- every tape started with that sound -- and begin to hold forth.
I do this with a friend in England that I met and became ultra fast friends with years ago. We traveled Asia together for 2 months. Haven't seen him in years and honestly might not again! But we are buds for life and keep in touch via async voice messages. The other day I sent him a short one asking a relatively intimate question and received a reply with an 18min message. Receiving it felt like Christmas.
The only issue is that people can't always listen, or speak, so they need to either just wait to reply, or you both need to switch to text often.
We tend to learn each other's schedules and then send messages based on availability.