A lot of years ago, one of my teachers used to use the phrase "book smart"
to describe students who could more or less memorize the text of a paragraph
or chapter, BUT not really comprehend the meaning and thoughts behind the
words.

These functions are exactly like programming languages.
There might be a hundred different ways to program an event to occur.

A function does something with the contents of cells.
As long as you know what it does (what's built into it), how you configure
the combination of the functions and their returns, is the measure of *YOUR*
ingenuity to complete an operation.

As you yourself just brought up, look at what the folks *here* have done to
the SumProduct() function, over and above what Redmond originally designed
it to do, as you can see by their very inept Help file on the function.

You have just paid for the tools when buying XL.
How well you utilize them is dependant on your talent and resourcefulness
(to learn from others - such as here).

Mark not sure what type of reply you are expecting... I only can tell
you 2 things:

1. I have more than a dozen programs which  core formulas containing
combinations of index, match, etc... So it depends of what you are
doing....

2. I wondered couple of years ago why to use the rank function.... last
week it came handy. Bottom line, probably there are many functions you
don't use (you don't have to !!) if you don't need them

Mika