I did the 2x8m FTP test (10min rest in between). That was after an hour endurance ride as a warmup. I know it’s not supposed to be an hr warmup but I didn’t have a trainer then so had to get to the spot I’d chosen to do the test. I had just got my power meter the day before. Like TrainerRoad’s ramp test, it’s only the final part (2min maybe) of each interval that is really hard. It’s not supposed to be easy 
I’ve loaded a 4x8m workout onto my Wahoo Bolt and will probably do it next week. I’ve set it at 10% FTP but will adjust if necessary.