diff --git a/requests/sessions.py b/requests/sessions.py
index 8c06448e..6570e733 100644
--- a/requests/sessions.py
+++ b/requests/sessions.py
@@ -97,6 +97,12 @@ class SessionRedirectMixin(object):
 
     def get_redirect_target(self, resp):
         """Receives a Response. Returns a redirect URI or ``None``"""
+        # Due to the nature of how requests processes redirects this method will
+        # be called at least once upon the original response and at least twice
+        # on each subsequent redirect response (if any).
+        # If a custom mixin is used to handle this logic, it may be advantageous
+        # to cache the redirect location onto the response object as a private
+        # attribute.
         if resp.is_redirect:
             location = resp.headers['location']
             # Currently the underlying http module on py3 decode headers