In answer to the original question.

Here's how not to work out how many games is enough.

Start up a couple of games. Get really impatient after the first month that they're only just getting going, and you want to play more SEIV NOW! Start a couple more games, including one 10-planet start which should be big from the beginning. Find you're enjoying it so much, you want to play MORE! Start up another game, and take over a couple of empires in existing games.

At this point discover that your original games have now matured to 90-minute-a-turn monsters, and you find that most of your spare time is spent feeding the SEIV beast. But it's still fun.

Then real-life intrudes, work gets busy, and suddenly the Last thing you want is two urgent deadlines a night, every night, when you get home.

Drop out.

This is a real story, it happened to - a friend. Yes, a friend. Heed his warning. Everything in moderation.