If you just use the amount given in the applicator, and at the frequency recommended then it should be enough for routine maintenance doses. However if as most of us do - you use it on the outside and also for the loading dose, or more than twice a week then you will need more.
16 doses = 16 applicators full so if used daily as a loading dose then would last 2 weeks 2 days only - that';s assuming you managed to get it all out of the tube!
However I don't use the applicator for mine and I can imagine squeezing the last bit out would mean it would run out before the two weeks was up especially as you are using extra.....
Hurdity x