When IMPORTRANGE is genuinely useful
If different teams keep their own separate spreadsheets, IMPORTRANGE lets you pull the source data into one combined report in real time, without ever copying and pasting -- so the report always reflects the latest numbers.
A couple of things that trip people up
If your spreadsheet's language or region setting uses a semicolon instead of a comma to separate function arguments, write the formula as =IMPORTRANGE("url";"range") instead. Also, IMPORTRANGE only refreshes when the destination sheet is open or recalculated, and pulling from many large ranges at once can noticeably slow a spreadsheet down.
Frequently Asked Questions
I granted access but the data still isn't showing up -- what now?
Double-check the range for typos, and make sure any sheet name that contains a space is wrapped in single quotes.
Does the linked sheet update automatically when the source changes?
Yes -- edits to the source sheet usually show up in the connected sheet almost immediately, though it can occasionally need a manual refresh.