You're off to a good start, but if you didn't complete the 20-minute test at 294w you don't have an FTP of 3.6 w/kg.
If you did, it would be .95 x 294w = 273w or 3.42 w/kg.
20 minutes is the standard, but there are eight-minute & ramp tests as well.
The drop off in what one can hold for 14:00 vs. 20:00 is significant, from my FTP tests I know that the first ten minutes isn't too bad, 10:00-15:00 is tough, and 15:00 to 20:00 is brutal.
I'm sure that I could hold well above my FTP for 14:00 but not last to 20:00.
FWIW I also have Xert's "What's my FTP" Connect IQ app on my Garmin, and that calculates an FTP based on shorter efforts, and is usually within a few watts of my "official" FTP based on a 20-min test.
Last edited by Dancing Skeleton; 10-27-21 at 06:28 AM.