I always have my phone with me. I text and use the internet on it the most. I use maybe 100 minutes a month I would say.
At my last job, we were allowed to have our phones when I started, then after a year they tried to start making us keep them in our cars or give them to a manager, I quit shortly after.
It's a security blanket, I don't want a family member to have to call someone else to get ahold of me in case of an emergency.