Back in the 50`s and 60`s I lived in a small community outside of Dallas !! Maybe 1500 people,, wasn`t very big but we had a recording studio !! Many of my friends and acquaintances made demo records !! As long as you had the money and your own music,,no problem !! I think they had a set rate for using the studio equipment and you bought the recording time !! Perhaps that why the time is recorded,, to remember when the session started or ended !!