For example, in Genesis 30:33, Exodus 19:10, 1 Samuel 11:10 and 20:18 a
QATAL with prefixed WAW (WEQATAL) is used with MXR. I take these as
perfective, but you do not accept this. ...
I'm not sure what David has said on this one. But if he is basically
supporting the four or five conjugation model, that does not imply that
he understands WEQATAL as not perfective. It is logically possible and
indeed makes quite a lot of sense for it to be non-past but perfective.
This is for example consistent with the usage in Exodus 25-30, where it
may also have a modal sense, whereas the corresponding clauses in Exodus
36-39 use narrative WAYYIQTOL in a way which is usually understood to be
perfective. Of course this is not what a crude "vav conversive" type
understanding might suggest, but as I mentioned before no one really
accepts that at least today.