Once in the morning, once after work, once some time later in the evening if you feel like it.
During working hours there’s rarely any reason to touch or check your personal phone (and in many professions you simply aren’t able to).
During after-work hobbies and/or family time you are for obvious reasons unable to have your phone on your person (it’s in a locker room, or you’re playing with your kids) or unable to pick it up (any creative or performing arts, or you’re having family dinner).