I seem to do boneheaded stuff all the time with cabling. Missing guides, ferrules, and/or all manor of installing stuff in the wrong order but not realizing it until I have cinched down the fixing bolt and can't get the dang thing to shift right.

Oh! and that one time I cranked on the crank arm remover so hard it pulled the threads out of the crank arm. Huh, I wonder why... Oh, forgot to remove the crank arm bolt.

There is also the classic installing the crank arms so that they both point the same way. It's gonna be a little difficult to pedal that way...