I think that totally depends on your phone and how old the phone is. I have an iPhone SE and I recently did a century ride with a friend, who's not that fast a rider, and the phone battery lasted me over eight hours. If I recall correctly, I had something like 35% battery life left at the end of the ride. I have a Wahoo BlueSC, Tickr, and RFLKT connected to the phone. On my daily 40-60 mile rides, I usually have 70-75% battery life left.

On thing you can do to extend your battery life is to go online and search for hacks for your specific phone. If you have an iPhone, turn off Notifications and Location Service for all the apps that you don't care if they know where you're at and don't care to be notified of anything. Force kill all your running apps except your cycling app before each ride and turn off WiFi. That will extend your battery life quite a bit.