Well in my case the system I chose has NSP's, Earthlikes, and a water world so I raced to claim it immediately. When I wrote down the system features I was in system and did not FSS and wrote down only 2 planets with geo signals and 3 with bio signals. I was about 100,000 ls from any of the planets with signals so I could not have been proximity revealing. Now after a few buildings placed I decided to review the system and was surprised to see like 5 more planets with geo signals. The NSP's have disappeared in the system and can't be found with any sensor or proximity (I have put in a ticket for this) so it is possible for systems to change features after being colonized. it could be that the stellar forge regenerates the system after being colonized and may change some RNG features after building. My main point is that I did not FSS and saw 5 planets with signals put them in my excel file then later discovered more planets with signals that I had wrote down as bare.