The OP's issue was covered and I had a closely/loosely
related question, so I hijacked the thread (continued it, but with a
slightly different issue) and decided to use the aparently obscure
term to indicate a change. Sorry. I thought it was didely known
within such educated circles as this. (;-)
Also, thanks to Wikipedia to know I used it correctly. Which makes
me wonder if there'll be a song for spelling Wikipedia...?
e-n-c-y-c-l-o-p-e-d-i-a (:-)
[[If you don't get this reference, you're too young to remember the
Micky Mouse Club TV show, but I digress]]

2- RE: Using Find, Autofilter, SpecialCells etc...
I don't know those, but am very comfortable with the sheet function
VLOOKUP...and didn't want to mess with trying to do the vba  version
discussed for the OP.

Also, I take Dave's comments as meant, to help, clarify. I *did* ask.

FYI: It works well for me. My reasoning was that the basic  Excel
formula functions  must be coded pretty tightly since they do lots of
computation in complex sheets and it all seems to happen very fast as
far as I can tell. In addition, the order of sheet operations must be
well organized for the sheet calculations to work correctly. So, why
not use that instead of code I write which must be interpreted (or so
it seems) and could be slow (since I'm still learning and without
formal VBA training) and potentially have errors which I'll have to fix.

3 - RE: Bouncing back and forth 'tween VBA & Sheet calc.
Uh.... See above.


4 - I thought my method was taking "advantage of the built-in features
of Excel (and VBA)"

I learned long  ago that there can be many ways to code a particular
solution and none are necessarily wrong, if they work. There are just
advantages and disadvantages and as long as the disadvantages are
acceptable/unimportant, go with it.

I'm not sure I understand " encourage bad programming practice". I
guess I was implicitly assuming that the Sheet function operates as a
subroutine which is already proven. I'm just calling it.
Reinventing the wheel and all that.
Thinking about the sheet functions, here's my rationale - right or
wrong. Sheet formulas  must be evaluated whenever a cell value change
occurs and in the order which allows proper propagation throughout the
sheet's (possibly) many formulae. Therefore, any change must be
handled completely and immediately after an input variable changes.
I get the impression that his thoughts are
from inference and his expierence rather than someting specified in
formal (uSoft) VBA training. Not to say they are not to be given some
weight, but not from specific, official cautions about the operation
of VBA/EXCEL.
If I continue to use this method and experience some problems, I'll
try to keep his cautions in mind and consider using VBA functions/code
to resolve them.