Having Unprotected Sex Twice Then Taking Plan B

If you were to have unprotected sex more than once, but took Plan B within 72 hours you had sex, will the pill still have the same amount of effectiveness? Or would you have to take Plan B twice? 
Would it still have the same amount of effectiveness if you had unprotected sex on Monday 10P and then again on Wednesday 6P and then again on Thursday 12P, but took the pill on Thursday at 5P (still within 72 hours)?