I saw in the previous question that EvalSumRows/Cols did not use hoisted rotations. Does EvalSum use this technique?
No, hoisted rotations are not used for EvalSum either (just like in the case of EvalSumRows/Cols) because there are no multiple rotations for the same ciphertext. Note that that EvalSum is used as a subroutine by both EvalSumRows and EvalSumCols.