I set up the SE4 quadrant data file to have a quadrant with only one system. Imagine a game with all 20 races starting in the same system. Imagine again each race starting with 10 homeworlds. Now that was some fast tactical mayhem.
Well, the idea isnt that bad after. A game with only 3-4 Systems, connected with each other. 10 races starting in them, and each sector offers like 15 planets. Engines or vessel speed in general would have to be decreased to maybe 1-3 per turn.