Maybe it’s more of me showing my naivety but I still think of a recursive function call as bindings and computation. My mental model is f(x) -> f(y(x)) = f(x) -> g(x), where g is a function wrapping the body of f. It’s surely not what the compiler does, but it makes thinking about recursion no more complicated than thinking about any old function. Then the only thing I need to think about beyond that is “does my environment support TCO, or am I certain my data fits in the call stack?”