When was the peak of Layered Products

I have various distros of the Software Product Library, and noticed
that, for example, there were a lot less layered products in the 7.3
VAX SPL than in the 7.0 VAX SPL. The 7.0 version contains notable
absences in itself (as far as I can determine), such as DECplan. I was
wondering what the collective opinion was on when the pinnacle of
applications available for the VAX was?

Indeed, I'd be interested to hear in people's opinions on their
favourite/most innovative VMS application that is no more.

Regards, Mark.
.