I agree with what (I think) you are saying! The cklist is not well written.
The way I read it, it runs in two parts:
1) In flight ie clean a/c
Follow drill for number of lights on o/head panel.
2) Then PLAN a F15 landing (ie runway length) because you do NOT know what is going to happen when you run the flap out
When you extend the flap, the cklist says " if the light remains .......", "carry out ........"
If the light is out with landing flap out, land normally. I would also have a 'shufti' at the o/head panel!