My old standard of when it was time to trim was when my hair would get stuck in the car door - as sometimes the hair has a mind of it's own and flies around behind me. Occasionally, when I sit on the train, parts of said hair will reach out and land on the shoulder of my seat mate. I always apologize and wrangle it back in. Today, I didn't notice the landing on the girl to my right. My hair wanted to make a new friend with her headphones. What followed was an interesting tug of war between she and I; me trying to get my straggler home, her trying to keep the headphone in her ear. I won, and the follicles returned home.
Yes, today we have a new standard. We're trimming this week.