Over torqueing? Possibly a great many. AN fittings are all over the place on aircraft though, and once you've jacked one up, you usually don't do it again. You get the feel for it. The hangars I worked in usually had a set of line wrench crows feet for torqueing fittings, but just like a car, or even more so in a little airframe, you aint getting a torque wrench on a large percentage of the line fittings. A lot of (most even) times too, you're working with aluminum tubing (not on brakes) for hard lines, fuel, hydraulic, pito/static, even high pressure air on turbine aircraft. I would never put an un-lapped aluminum flared solid line on anything.

Basically, if you're an Ug-wrench, you won't last long working on aircraft. Most everything is aluminum and you'll only spend so much time fixing stripped and broken off stuff before the boss taps you on the shoulder and you're cleaning spark plugs and moving airplanes around.