Running straight & fixing defenders is a skill that all players must learn and learn at an early age. The top players regularly practise this skill to maintain accuracy. This is the building block to scoring tries
Now working in just twos, we are concerned with depth, and the timing of the pass. Allow players to practice before adding a static defender. This can be a tackle bag as demonstrated. Players take the ball up to the defender but must complete the pass before they reach it.
A development of the 2 v 1 and 3 v1 drills, the attackers now must beat 2 defenders. This requires more decision-making ability as the movements of the defenders could change every time. Players must communicate as well as continue to perform their handling and running skills.