If you've tried to make formulas in Google Sheets using the
ISBLANK() function, you probably have noticed its wildly unintuitive behavior: it does not consider
"" as blank. No, that's not two visible quotation marks – that's the presence of the string delimiter. So cells with the contents (omitting the initial
" used to display the formulas)
To mitigate this problem, use
EQ(LEN(A1), 0), which does what you expect.