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
Oh no, I got the meaning of the idiom from context. I was asking about the actual phrase Yak shaving. Where did that part come from? So thanks for the second link. Not quite as interesting as I was hoping.