Recursion Tree Analysis by Leaves
The master theorem is a very thorough answer to this question.

Let us consider the three cases of the theorem, as applied to the recurrence $T(n) = aT(n/b) + f(n)$:


$f(n) \ll n^{\log_b a}$: in that case most of the work is done at the leaves.
$f(n) \asymp n^{\log_b a}$: in that case the work done at all levels is similar.
$f(n) \gg n^{\log_b a}$: in that case most of the work is done at the root.


Other recurrence relations behave differently. As an extreme example, there is no natural Case 1 for the recurrence $T(n) = T(n-1) + f(n)$.