In my professional work, I've seen this particular sin most often in the form of "refusal to use floating point (due to lack of proper understanding of the limitations leading to a fear or dread or just undue reluctance to use floating point in so many situations where it would be better than some integer, usually in a poor choice of units)".

not understanding the limitations of floating point!

Just floating a point here: Floating points are not limited. Computer implemented floating point math, however, is.