What's the most rational way to remove back hair?

I have plenty of annoying back hair that I need to get rid of. Through monthly calculations, I've found that they grow at an average 1.23 cm/month, and have a tendency to curl into black wisps.

Further Bayesian calculations have shown that the empirical probability of getting noticeable hair in my lower and upper torso is 0.8 and 0.63 respectively during the summer season.

I would like to inquire about the most rational length to which I should trim my back hair (I have a Vernier Caliper and extremely sharp scissors), and the recommended duration between successive trimmings.

I'm sure that the rationalist community here can help me make the most rational choice in back hair removal. As a Bayesian myself, I greatly prefer the use of Occam's Razor, and would appreciate simpler answers.