2 or 3, need to know. or is this an originality forum question?

Mine had 3.

I think you could actually get by with just one in the center as the vertical trim seems to hold down the edges.

I would use more than that. Mine had 4 if my memory is correct. The top seal sits on that so there is a need for firm attaching.

I'd vote for four clips as well.

I had 3

I also had 3.

3.
CCL

I think that settles that.

Every one I ever took off had 3.

Mine had 2, but there were signs of a thrid (that the dumb PO lost).