Even if you use the very best roofer in your area, keep an eye on their work. Many years ago we owned a house with a gable roof and a gable front porch. Roofing crew started working on each end as you would expect them to do, but when they finished, one end had one row more than the other end and they tapered that row so it disappeared at the middle of the ridge. Looked horrible. Roofer asked me what I wanted them to do and I calmly told him to take it all off and start over. He did, and got it correct the second time.