Starting with a simple idea that could theoretically be completed by a simple task, but as you implement it, reality complicates and sends you off on many deviations from the original straight and narrow path.

Yak shaving could be required and unknown at the beginning, or it could be a lack of discipline leading to scope creep - often it's both

The famous Malcolm in the middle scene for ref: https://youtu.be/AbSehcT19u0?si=Pchmbf3509l1CbeQ - but the term was originally coined from elsewhere: https://en.m.wiktionary.org/wiki/yak_shaving