What's the meaning of “all too often”, for example, in this sentence?

Question

What does "all too often" mean in this sentence?

A poorly designed distribution system can ruin the performance of any water-based system. All too often, people, including heating professionals, focus their attention on water-based heat source selection and simply assume that heat source ...

Answer 1

The all is frequently added to strengthen an expression. It means entirely, thoroughly, very, completely, totally, much.

• I was all alone
• The rum is all gone!
• He was all too happy to see me in trouble!

Answer 2

According to NOAD, all too is an expression — "used to emphasize that something is the case to an extreme or unwelcome extent:

failures are all too common."