I just found and watched this new interesting video about the techniques some companies used to improve duplication of pre-recorded cassettes at the start of the 1990s just as the market was starting to decline. Its worth watching for some of the figures like how much a Cassette cost to make and how many were sold each year. If you have plenty of time there are lots of other good audio related videos on the Techmoan channel.
This is another great video by Techmoan. I have links to the most interesting and related to cassettes in my blog. Take popcorn and enjoy Ps: in one recent video he shows two tapes I gift him
