How often does the game end by score/time?

For the first time my game is about to end by time. I've got 21 turns left on king and epic speed

Not often. I cannot recall winning/losing that way in years. On higher difficulties, someone usually wins a victory condition before then.

Never myself, saw it happen once for my gf on King.

Shouldn't happen in my opinion, King AI should win before time limit.

In my game with Poland, Morocco has been dominating the game, we're only left with 3 civs and Portugal with her 2 population city. Morocco would almost definitely get every other VC first if it was't for time. I'm desperately trying to take his cities to boost me ahead of him on score