Is the “C” of the model always indispensable ?

I often notice in my practice that “clients” starts with a (quite general) Thought (or Action).

Example: “I have difficulties speaking in public” (for me, that’s a T, right ?)

Do I necessarily have to go and find a specific circumstance (C) to handle this problem? Or can I “unroll” the “Feeling-Actions-Results” of the model without looking for a C?