Well... did u see one interesting thing? It's that our hope of of taking 20 wickets actually is lost behind our Poor Batting and not our bowling!
We usually dont need to take 20 wickets in tests. Because when we bat first we fail to cross the Lead Imposed by the Opposite Stronger test team even after our 2nd innings of bat... so we dont need to go for the later 10 wickets of them!
And when we bat second... we are usually enforced to follow on and again fail to cross the opposition's first innings score with our second Innings runs... so even then we dont need to try for their 2nd 10 wickets!
So the first thing we need to do to take Opposition's 20 wickets... is to score enough runs when we play our first innings!