Cyclocross Race File for Estimating FTP?

Advised? Useful? I have a power meter on my cross bike, and have looked closely at the files from the first few races of the season. Trying to decide if they are useful for estimating current ftp, and if so, how. Specifically, would the norm power or average power be a better estimate, should I reduce the number by 5% as with a typical test? Other considerations? Thanks!

Cyclocross race is probably one of those races you would have a hard time coming up with an accurate way to measure your FTP. Your power is so variable with the ON / OFF, can see this as VI in TrainingPeaks. And also you actually are off the bike at times.

So in a criterium, road races or group rides we have riders look at your their norm power for 60 minutes. It really needs to be 60 minutes to use normalized power. If you are looking at your peak 20 minute power you need to take off 95% of that.

But you can absolutely get your threshold heart rate. Power will be very up and down but heart rate will be more consistent throughout the race and is a good gage of the effort.