diff --git a/spec/helper.rb b/spec/helper.rb
index 066a855..09a09a9 100644
--- a/spec/helper.rb
+++ b/spec/helper.rb
@@ -311,7 +311,7 @@ def postgresql_explain
   end
 
   def mysql2_explain
-    seed_rows! # MySQL needs a bit of data to reach for indexes
+    seed_rows! if Delayed::Job.none? # MySQL needs a bit of data to reach for indexes
     connection.execute("ANALYZE TABLE #{Delayed::Job.table_name}")
     connection.execute("SET SESSION max_seeks_for_key = 1")
     connection.execute("EXPLAIN FORMAT=TREE #{sql}").to_a.map(&:first).join("\n")
@@ -325,7 +325,7 @@ def sqlite3_explain
 
   def seed_rows!
     now = Delayed::Job.db_time_now
-    10.times do
+    100.times do
       [true, false].repeated_combination(5).each_with_index do |(erroring, failed, locked, future), i|
         Delayed::Job.create!(
           run_at: now + (future ? i.minutes : -i.minutes),