The drills here are practicing the inital blocks from attacks. If you cannot block well, the counter movements you learn will not be effective - if you are good at blocking and mess up the counter, at least you will have a second attempt. These drills can be used in two ways:
1. With a partner. It is always better to learn these with a partner to get used to how fast the attack will come out, timing of your block with their attack, and the force required to block. It is also fun to practice with someone and discuss aspects of the technique.
2. Alone. Once you have learnt the blocks and have got used to them with a partner, the more you practice, the faster you will be. Any time you have 15 - 30 seconds, you can practice a block a few times.