I played a game of power grid with 6 players using the map of Italy, with one zone removed. In step 2, I had power plants to produce electricity for 11 (6-4-1) houses with cheap resources, and built 13 houses, preparing to end the game (14 houses) once a suitable plant is in the market. However, one of the players had plants to power 15 houses, so I didn't buy a 4-house plant in the market, fearing that once I bought it, he would build up to 15 houses immediately to win the game (he had 11 houses at that time), and waited for better plants.
Afterwards, step 3 was entered. My player order was 2 at that time. I bought a 6-house plant, replacing the 1-house plant, preparing to end the game with 16 houses, fully powered. However, the other players had filled in all the cities in the map immediately, with no more space left, making me unable to build the 3 additional houses to win the game.
Is this a rare scenario? Can this happen when everyone plays the game normally? Should I instead try to end the game earlier when I already had 13 houses?