The fact that 4000m was experienced on one METAR does not mean that these conditions didnt materialize frequently or infrequently between routine observations!
Absolutely correct.
For the purpose of this thread I needed to accept this shortcoming. A lot of significant weather is hidden in SPECIs, which never leave the airport. METARs are only helpful if seen in context with the general weather situation.
For this reason I always check a lot of reports from the area in question, check a couple webcams I trust, have a look on RADAR, have a look on vertical soundings, maybe near-infrared satellite imagery or visible imagery... This way I try to get a feeling how frequent especially the minor nuisances may occur. Hundert percent certainty will never arrive.
I wanted to illustrate, that it is impossible to write the "perfect" TAF. Wether you perceive a TAF as helpful or not depends to some extent on your intentions and other personal variables.
And some TAFs just turn out to be not helpful at all. I'm honestly sorry about that.