I beg to differ, my friend. You're introducing additional means of contraception, which has already been discussed as improving efficiency even more. Yes... combining a 99% effective method with *anything* else will increase its effectiveness above 99%.
I truly hate statistics... hated it in university three times, and each time I thought I was done with it forever. It kept coming back because it still works.
99% effective means one time out of 100, on average, it will fail. In some cases, it may go longer. In others, it may go less. But on average, one time out of 100, it will fail.
Therefore, if you have sex 100 times with a 99% effective method of contraception, that means that one time out of 100 it will fail. By definition. If it fails more often, it's not 99% effective. If it fails less often, it's also not 99% effective.
I do agree that it's better than doing nothing... "Nothing" is only around 15% effective, which means that you shouldn't have to go more than two months or so....
And please, before anyone takes the "I know someone..." argument: Yes, you do. That's the idea behind statistics and averages. Individual cases can go all over the place. En masse, however, the results will tend toward a statistical number. And statistics is the art of finding that number to try to do something useful with it.