I have a popular one, and they are rubbish.
Imagine you can sell small business accountancy services for £300 a year; and you can hire an accountant for £40,000 salary for a 2,000 hour year. Add on an extra £10,000 for tax, insurance, office space, parking, advertising, and things like that.
If you do an average of 6 hours of work for each client each year, your accountant can serve 333 customers and bring in £100000 a year, making £50,000 in profit.
On the other hand if you automate heavily and get rid of all the customers who have complex needs or who are calling you a lot, so you do an average of 15 minutes work for each client each year, the same accountant can serve 8,000 customers and bring in £2,400,000 a year making £2,350,000 in profit.
I know how I'd run my accountancy business, if I had one!