It's a way to test if your ftp is exactly 350w. You will not know if you could have done slightly more, or if you fail to do 20 mins you will only know that your FTP is NOT 350w.
But you could switch off ERG if about to fail and grind out whatever you can until 20 minutes is up I suppose.
@TTM started
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It's a way to test if your ftp is exactly 350w. You will not know if you could have done slightly more, or if you fail to do 20 mins you will only know that your FTP is NOT 350w.