Carl Rogers (1957) believed that 6 core conditions were necessary and sufficient for therapeutic change to occur. Thus by default he also believed that there is no need for fancy techniques, or ways of working. So, so long as the 6 conditions exist in whatever model of therapy then, he believed that over time 'therapeutic change' would occur.
I believe that these conditions seem to be taken for granted by other more cognitive models. Some therapists may not even be aware of the existence, let alone importance of the conditions, as technique or 'case formulation' takes over the therapy.
Chris Rudyard MBACP
Professional, experienced counsellor/psychotherapist in Liverpool