Excellent easy to understand advice. It could apply to investing or to buying a house ( which is just another long term investment) or to budgeting your finances in general .
Why is a price to earnings of 10 or less a bad investment. There are many blue chip stocks that go to below ten and then it is a great investment. That advice makes it sound like a P/E or 126 is better and we know lots of investments with that where people have lost their shirt. That advice is poorly explained and very dangerous