Building Scouting Knowledge

I am currently in a save with Leeds, and I am trying to build as broad a scouting network as possible. I send scouts out to countries, they gain full knowledge of that country, give me player reports then I re-assign them to another country. This is all fine and well but after two to three weeks the scouting knowledge of that country appears to get gradually lower and lower, is there anyway in which once I gain full knowledge of a country that I can preserve that?

Get a staff member from that country. AFAIK that's the only way.

Surely this is something that needs looking into? After a few years scouting the same region would the scout not have the same knowledge as someone who was from that country via contacts etc? Also why should someone have full knowledge of a country they have not lived in for years? Doesn't make sense to me!