Hmmm.... I'd caveat that advice a bit. I'd have to be pretty sure that the company I'm copying is facing the same sort of problems I am. Especially since, after N instances of being wrong, I've learned that I'm often quite bad at figuring out whether company Foo is facing the same problem as company Bar!

Especially when you have limited resources and solving one problem means that you're not solving another.

I've seen far too many instances of people coping what Amazon or Facebook do and it not helping in any way because - well - they're not Amazon or Facebook.

Personally I'd try and spend a more time talking to / observing actual users if I don't have the numbers for more quantitative techniques. Something, sadly, most companies seem to do just about as much as they a/b test :-/ That'll give me some strong hints on what the most significant problems are.