Scout knowledge decline.

Having given up on scouting regionally (where they repeatedly scout the same nation and often don't end up with full knowledge of where they've scouted) I've decided to scout by nation individually.

I'm having two problems though:

1) Why has my scouting knowledge of French Guiana dropped to 75% one month later? Do things change so rapidly in Guiana that 25% of the entire game has changed in a month. I can understand scouting knowledge decreasing with time but I don't expect to have lost 25% of my knowledge in a country where I suspect not 25% has changed.

2) Which brings me onto my second point. After scouting individual nations the knowledge declines over time, as mentioned before. But why does Giovanni Elber lose his knowledge at such a rapid rate (he scouted French Guiana) comapred to the others. Is this in any way regulated by their stats?