It’s like one of those universal truths. Anyone who’s ever done an inverted flare has done it without the nut on there first. These are usually you best flares as well. You look at it admiring how perfect it came out, and one second later you realize there’s no nut there.
When I first started doing brake lines I left the nut off about 25% of the time
After 20 years I'm down to 10%