CBT works well in conjunction with traditional talk therapy for self esteem - it doesn't need to be one or the other. Poor self esteem is often the result negative beliefs that we internalize, sometimes starting in childhood and sometimes later. I don't think it matters so much how long you've had these beliefs as it does how you think and what motivates you. CBT can be succesful because its action oriented and people who like it like the direct tangible nature of it. I think whether you prefer traditional CBT or a combo with something else really depends on your personal style.