Pro tip: I was sanding a quarter panel for way too long because I didn't know about the right grit jump

I was blocking out a repair on a Honda Civic's fender last week, starting at 180 grit. I kept going up to 320, then straight to 600 before primer, thinking it was smooth enough. The painter, Mike, came over, ran his hand over it, and just said 'you're leaving scratches, man.' He showed me his method: 180, 220, 320, then 400 before the 600 step. The 400 step made all the difference. Anyone else have a specific grit sequence they swear by for metal work?