diff --git a/app/jobs/domain/fa/job/user_page_job.rb b/app/jobs/domain/fa/job/user_page_job.rb
index 0de99ff2..b57e8b78 100644
--- a/app/jobs/domain/fa/job/user_page_job.rb
+++ b/app/jobs/domain/fa/job/user_page_job.rb
@@ -1,5 +1,7 @@
 # typed: strict
 class Domain::Fa::Job::UserPageJob < Domain::Fa::Job::Base
+  RECENT_USERS_THRESHOLD = T.let(12, Integer)
+
   queue_as :fa_user_page
   queue_with_priority do
     T.bind(self, Domain::Fa::Job::UserPageJob)
@@ -167,7 +169,7 @@ class Domain::Fa::Job::UserPageJob < Domain::Fa::Job::Base
     if recent_watching.empty?
       logger.info(format_tags("skipping followed users scan, 0 watching"))
       user.scanned_follows_at = Time.current
-    elsif recent_watching.count < 12
+    elsif recent_watching.count < RECENT_USERS_THRESHOLD
       logger.info(
         format_tags(
           "skipping followed users scan, #{recent_watching.count} watching < threshold",
@@ -215,10 +217,16 @@ class Domain::Fa::Job::UserPageJob < Domain::Fa::Job::Base
   end
   def check_skip_followed_by_users_scan(user, user_page)
     recent_watchers = user_page.recent_watchers
+    page_num_watched_by = user_page.num_watched_by
+
     if recent_watchers.empty?
       logger.info(format_tags("skipping followed by scan, 0 watched"))
       user.scanned_followed_by_at = Time.current
-    elsif recent_watchers.count < 12
+      return
+    end
+
+    # by now, we know that there is at least one watcher
+    if recent_watchers.count < RECENT_USERS_THRESHOLD
       logger.info(
         format_tags(
           "skipping followed by scan, #{recent_watchers.count} watchers < threshold",
@@ -239,36 +247,34 @@ class Domain::Fa::Job::UserPageJob < Domain::Fa::Job::Base
         unique_by: %i[from_id to_id],
       )
       user.scanned_followed_by_at = Time.current
-    elsif recent_watchers.any?
-      # if there are watchers, find the ones we've already recorded. if
-      # all of them are known, then we can skip scanning favs the next time.
-      known_watchers =
-        Domain::User::FaUser.where(url_name: recent_watchers.map(&:url_name))
-      if known_watchers.count == recent_watchers.count
-        logger.info(
-          format_tags("skipping followed by scan, all watchers already known"),
-        )
-        user.scanned_followed_by_at = Time.current
-      end
-    elsif recent_watchers.any?
-      # if there are watchers, find the ones we've already recorded. if
-      # all of them are known, then we can assume watched users are up to date.
-      num_recent_watchers = recent_watchers.count
-      num_recent_watchers_known =
-        user
-          .followed_by_users
-          .where(url_name: recent_watchers.map(&:url_name))
-          .count
+      return
+    end
 
-      if (num_recent_watchers == num_recent_watchers_known) &&
-           (user.followed_by_users.count == user_page.num_watched_by)
-        logger.info(
-          format_tags(
-            "skipping UserFollowsJob, all watched users already known",
-          ),
-        )
-        user.scanned_followed_by_at = Time.current
+    # if there are watchers, find the ones we've already recorded. if
+    # all of them are known, then we can skip scanning favs the next time.
+    known_watchers =
+      Domain::User::FaUser.where(url_name: recent_watchers.map(&:url_name))
+    if known_watchers.count == recent_watchers.count
+      logger.info(
+        format_tags("skipping followed by scan, all watchers already known"),
+      )
+      user.scanned_followed_by_at = Time.current
+      return
+    end
+
+    # is the recent watcher in the last position known?
+    last_recent_watcher = T.must(recent_watchers.last)
+    last_recent_watcher_is_known =
+      known_watchers.any? do |user|
+        user.url_name == last_recent_watcher.url_name
       end
+
+    if last_recent_watcher_is_known
+      logger.info(
+        format_tags("skipping followed by scan, last watcher already known"),
+      )
+      user.scanned_followed_by_at = Time.current
+      return
     end
   end
 end
diff --git a/config/routes.rb b/config/routes.rb
index 93226524..34c87c14 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -1,4 +1,5 @@
 # typed: strict
+ID_CONSTRAINT = %r{([^/]+)}
 Rails.application.routes.draw do
   mount ActionCable.server => "/cable"
 
@@ -24,6 +25,9 @@ Rails.application.routes.draw do
   resources :users,
             as: :domain_users,
             only: %i[show],
+            constraints: {
+              id: ID_CONSTRAINT,
+            },
             controller: "domain/users" do
     get :search_by_name, on: :collection
 
@@ -48,7 +52,13 @@ Rails.application.routes.draw do
            as: :visual_results,
            to: "domain/posts#visual_results"
     end
-    resources :users, only: %i[], controller: "domain/users", path: "" do
+    resources :users,
+              only: %i[],
+              controller: "domain/users",
+              path: "",
+              constraints: {
+                id: ID_CONSTRAINT,
+              } do
       get :faved_by, on: :collection, action: :users_faving_post
     end
   end