Upstream or Downstream Approach

Is is best to fish upstream or downstream when wading to fly fish for smallmouth bass? By wading and fishing upstream you are less likely to scare wary bass. Therefore this is often my favored method late in the season when the streams are low. Wading and fishing downstream and down and across stream simplifies some fly action such as skating big drys and swimming streamers. And some anglers find this approach make it easier to detect strikes and set the hook.