Literature would tell that CBT is one of the widely used and researched therapy, but there are also claims that it has already lost its efficacy throughout time.
Cognitive-behavioral therapy (CBT) is a psycho-social intervention that has different aspects and contexts. All behavioral outcomes as result of therapy or exposures/ factors could have ecological and temporal conditions leads to decline. Cognitive-behavioral therapy (CBT) differs from cases to cases and exacerbating factors should considered. The cognitive behavior therapy approaches variation could be another consideration along with types of mental health disorder to be treated.
CBT is considered "gold standard" in working with many anxiety conditions, especially phobias. It is also considered effective in many cases of uncomplicated depression. There are recent modifications (e.g., the incorporation of mindfulness practices in some forms of CBT) and extensions to additional diagnoses, but it's my impression that the longer-standing applications remain highly regarded for their overall, evidence-based effectiveness.
Does Cognitive Behavioral Therapy has loss its efficacy in dealing with mental disorders?
As previous answers have said, the efficacy of CBT has not been lost. For various disorders CBT has been shown to be effective. Please see our meta-analysis of CBT’s efficacy for bipolar disorder here:
Chiang, K.J., Tsai, J.C., Liu, D., Lin, C.H., Chiu, H.L. and Chou, K.R., 2017. Efficacy of cognitive-behavioral therapy in patients with bipolar disorder: A meta-analysis of randomized controlled trials. PloS one, 12(5), p.e0176849.
Hsu, H. M., Chou, K. R., Lin, K. C., Chen, K. Y., Su, S. F., & Chung, M. H. (2015). Effects of cognitive behavioral therapy in patients with depressive disorder and comorbid insomnia: A propensity score-matched outcome study. Behaviour research and therapy, 73, 143-150. https://pubmed.ncbi.nlm.nih.gov/26313621/