Confidence evolves slowly.
Just as becoming more flexible physically takes time and effort, trust in your technique grows in similar, often imperceptible degrees. Recently, I attended a seminar and found that while half of the material came naturally, the other half took time and I had many questions (any of us who try new things in the MA world know our ego is best left off the mats in order to truly learn--and after all, if you knew the stuff already, why would you be there in the first place?). And while, in the end, I managed to understand the teachings, I would still hesitate to use some of them in any stressful situation.
However, I plan to take the lessons home and think about them and practice them many times. I know from experience that some of the most reliable techniques in my arsenal felt this way at first--unnatural. I know this is how our mind's tend to expand--gradually--in order to really have the lessons sink in.
If I look back, even previous to my formal training, I can pick out things I learned from grade three judo class or grade nine wrestling that are imprinted in my mind. Techniques I would still likely revert to in stress, as I worked them into confidence over the years.
And by degrees, I have added more and more.