Paired sequence drill is a good way to train techniques as it allows you to apply what you have learned in a controlled setting. In class, usually we start the drill with something relatively simple, and as the class progresses, we add more and more to the sequence. Example of this is the below sequence:
Start with a relatively simple one-two step, and keep adding to the sequence. The first drill below is not the first series of the drill, but perhaps no. 2 or 3 (i.e. start with the first 2 sequence, then 4 sequence etc.)
As the techniques kept getting added to the above drill, the final sequence drill built up to be the following: