I have done a couple of Ramp Tests recently and got an FTP of 240 and 241W respectively. It was nice to see that this has gone up from 220W previously but in reality there is absolutely no way I can maintain 240W for an hour (just like I could not hold 220W when that was my FTP according to Zwift). At the same time, Garmin gives me my current FTP as 214W but I have managed to ride at 225W in ERG mode for 60 minutes. From the above I assume that my real FTP must be a little over 225W.
I am wondering how many riders here can actually ride their calculated FTP for 60 minutes?
Long story short, your FTP isn’t “one hour power”.
Use the value given by whatever test you prefer to set your workout targets. If the workouts are too hard, then adjust it down a few percent. If the workouts are too easy, then adjust it up a few percent.
As long as you consistently use the same FTP test, you can measure your relative progress. The actual number doesn’t mean a whole lot. Like Lin_alan mentioned, just adjust your workouts was needed.