We have months because there is a big celestial body close to our planet that helped humans track long-scale time since before any formalized time system, so we

We have months because there is a big celestial body close to our planet that helped humans track long-scale time since before any formalized time system, so we had to fit it in, but on Mars? Even though there are Phobos & Deimos (which orbit too fast for any similar long-scale time tracking practical purpose), how visible are they to a martian surface observer with unaided aye? I guess that indeed there probably won't be anything, or at least not something local for that time-scale.