Blocking in my opinion is one of the more underrated aspects of table tennis. During a practice session players mostly focus on offensive techniques such as looping or smashing, but it is equally important to develop a solid blocking game in case your opponent in a match situation is much more proficient at initiating or executing attack shots. For some players, blocking is an integral part of their game, as it is for Kenta Matsudaira of Japan. He shows great form in blocking as he constantly moves around to adjust to the placement of each shot, staying on the balls of his feet. He also maintains a comfortable distance from the table as he waits patiently for the opponent to attack, and does not often resort to backing off the table to try for a more defensive shot such as a lob or fish.
A common mistake I have seen at intermediate and lower levels is that a player’s block is hasty and rushed when the opponent attacks strongly. It is important to maintain a pace and distance from the table that you are comfortable with so that you can dictate the point with your blocking, and not just react to what your opponent is doing. In some cases the block can even be used as a weapon, using placement and speed to throw off the rhythm of your opponent, just as it does for Matsudaira.
In situations where you cannot attack, blocking can be an effective and useful tool to complement your game. Try it out and see if it works for you.