Partly as I wouldn’t really know where to stop…
You sort of leave a pair of “hair shorts”. Go higher up the outside than inside but on the inner thigh, stop well before you get to that horrible itching of hair growing back in awkward places.
But don’t then go and wear a pair of Speedos, hair shorts look very wrong!
I do mine in summer but then just let it grow over winter. Usually my last shave of the season is the day before the Three Peaks CX and my first of the year is just before the Eddie Soens (if I’m actually racing the Soens). I do ride track but don’t do track racing anymore so no real need to shave over winter.