It is certainly possible, Charles Dearing says he has never use a flat blade. I am building a fret work box, I say building, I have finished all the scrolling, shich I did with 3/0 spiral blades, but I still take it out and sand on it occasionally. Why, because I could not get as clean cuts as I would have had I used a flat blade, not as sharp pointed inside corners and a ton more fuzzies to clean off. Fact this is the project that taught me I need to start learning flat blades, which I have done. But it is to each his own. I love spirals, but now I love flat blades also. They both have their places.
By the way, I watch a Charle Dearing video or something where he said he could get a sharp inside cut with a spiral. I have tried and tried to do what he said, but I have been unable to do it. I keep trying, maybe some day....