We mainly use the fix page to cross check the FMC derived position against actual "raw data" position.
Whatever waypoint or beacon you put inthe fix page will result in your FMC bearing and disyance from it being displayed.
We put in a VOR in the Fix page and compare the range/bearing with that displayed onthe Nav set.
Other uses for the fix page are to highlight a particular waypoint (the fmc puts a green circle around the point on the map page) for example critical waypoints in an emergency turn procedure or go-around.