I have my Facebook set with Notifcations disabled, messenger location services turned off, and a 1 hour refresh interval. That keeps its battery use pretty low; however, I may not use it as much as you.
I basically check it once in the morning (because my friends will get mad at me if I miss their "really cool post"). Then I might check it once more during the day. Today, it used 5% of 26% of my battery over a 14 hour period.