Probably, I’m surprised at the claimed RCS, it seems high, but the grouping if you will is likely correct.
It’s simply a matter of size, majority of
Radar reflectors just simply aren’t big enough to really add all that much to an average
fiberglass boat with a
mast and
rigging.
To really increase your visibility by a significant amount, you need one that would be objectionably large.
Unless you go active, then of course it’s not size, but
transmission power that determines perceived size, a powerful enough transmitter could make you as visible as a Super Tanker.