How many nations?

I'm starting a career with a Segunda División B team in Spain with the goal to take them to the top. How many nations do I really need? I want good talents from Brasil, France, Italy, Germany and Argentina, but I'm not going to play with another team.

With Portugal, Spain, Argentina, Brazil, England, France, Italy, Netherlands, Spain and Germany I got 51 000 players and three star game speed.

That sounds fine tbh.

Just to be sure, what are your specs?

I use a Mac but don't have any idea about my specs...

Do you know what's the difference is between visible and playable countries/leagues when it comes to player development? Do players develop more slowly or not at all when the league is just visible?

Players should develop at the same rate in playable and non-loaded leagues, however you will have a far larger database in the country to build on if you load its leagues as opposed to if you didn't.

If your system is good enough, I'd load a large database and perhaps also load a custom database with players from top clubs or with a national reputation in both South America and perhaps even North and West Africa.