Not just an opinion. It is easily measured, and has been frequently. We're
talking about writing, not speech, and specifically acronyms and
abbreviations that need explaining.
It might be easier for you, as writer, to use DIRSSP, but for the reader
"Directory Strategic Systems Progams" is obviously simpler. And indeed, the
saving for you is likely a fiction anyway: the extra effort for you to spell
it out is minimal, and a great deal less than the extra effort to maintain
and cross-reference an accurate glossary. Worse, most people won't refer to
your glossary, so you've now introduced a significant source of error and
ambiguity.
There's a whole website somewhere of sanfus (some of them fatal) resulting
from people guessing wrongly what an acronym meant.