You start with 5 cards in hand and from the first turn have 5 power points and 1 extra card.
How many turns does it take to empty your hand if you play 2 cards each turn? 4!
What does this mean? that you MUST have 5 power point cards well balanced, spend 2 power point for extra draws or at some moment of time use the power points for special abilities instead of playing cards.
Actually, I believe you can play two cards 5 times, but this does not really change your point. Moreover; unless you either draw cards or skip playing a card some turn, you will always exhaust your hand after five rounds of playing two cards -- the number of rounds playing 5 point cards does not change this.