If you get one through, it is extremely rare.
I actually write quite a bit of business where other agents (and DIY) drop the ball. Fortunately, most of my clients are routine, but I do take on more than my share of challenge cases when I know there is a chance of getting coverage.
I usually get it right the first time, but did have a 63 yr old with polyps (twice removed including during a colonoscopy a few weeks before applying for coverage) that I had to go to 3 carriers before getting him full coverage.