I read online that ADO is unable to write to a closed spreadsheet.
I don't know if this is true or not, but if so, I'm considering an
alternative method.

I figure I can use VBA to open, update, and close a spreadsheet,
while turning off screen updating. The update is a quick operation
that only writes a number into one specific cell. This will work okay.

But....suppose the target spreadsheet is open by another user.
Would it be a good idea put my VBA script on a short timer that
constantly checks if the spreadsheet is open by someone else? Then,
once the spreadsheet is closed, my script can do its own update
operation, and then close the spreadsheet for other users.

This is basically a situation where multiple users will be attempting to
write to a single spreadsheet in a first-come, first-served basis. I'd
appreciate any tips on how to make this function smoothly.
Thanx guys & gals!!!