Neteller netpoints cash giveaway

some notes on it->
- there are 3 giveaways.
weekly = 1000 points for $500
biweekly = 2500 points for $1000
monthly = 5000 points for $3000

- The prizepool doesnt vary
- Each neteller user can enter a draw as many times as he wishes insofar as he uses enough netpoints to do it.
- The amount of contestants entered in each draw varies


My question is: What should be my strategy for maximizing my return here? Should I merely save up X amount of netpoints, wait until entries for a certain draw is number Y (any ideas to what that number is?), and then dump all my netpoints onto that one draw?