What's the use of the block Set Spreadsheet.Sheet Name to

I have a Spreadsheets (Cloudstitch) component it refers to a spreadsheet with 10 sheets and in my app I want to (depending on a choice made by the user) write data to one of those Sheets.
Is my understanding correct that for each Sheet I have to make a seperate SpreadSheet object?? What is the purpose of the Set Spreadsheet.Sheetname block then.
It works for reading from the spreadsheet. Why doesn’t it work as well for writing to it? Or am I missing something?

This has been my experience anyway.

It’s just an alternative to setting it in the Designer I suppose…Perhaps if you had two endpoints you could use one as an spreadsheet index of sorts. The user could select a sheet name from a list picker. Based on their selection you could then go and get the correct sheet from the second endpoint?