It's not just airspeed, centerline, and approach.
Aimpoint(trend?), alignment(trend?), airspeed(trend?), variation from projected descend path(GS,VASI,PAPI,VTI, FMC deviation from path)(trend?), sink rate(trend?), power(trend?).
Any adjustments made? Verify the trends changing due to the adjustments made. And one adjustment often changes at least one, and possibly several of the performance criteria you're monitoring.
Cycle through the scan again and again and again and again until touchdown.