That's good advice.
You need to think of buying a box or case as similar to buying a lottery ticket (although a lot more expensive). Everyone hopes to win, but few do. If you don't have a lot of money for cards, you have to weigh what it will cost to buy the individual cards you want versus the thrill of opening boxes and not knowing if you will pull a big auto/variant prop
or get one or two inserts that are worth less than half what you paid for the box.
Personally, I have absolutely horrible luck with HP boxes. I reached the point over a year ago where I realized that, for me, it wasn't worth buying boxes.