Why do we do them? Which ones are right for you? Why not just swim rather than drill?
Drills are exercises designed to isolate particular movements of a whole stroke and work on making that movement better. When we always do the entire stroke, there is likely to be reinforcement of any flaws over and over again. It is easier to fix a technique problem by isolating the component and practicing it correctly.
Which drills you do when given a choice should be determined by those things in a particular stroke which need improvement. For example, if you tend to drop your elbows in freestyle, the "finger sweep" is great to do, or if you canít get the hang of the dolphin motion, the "rocking horse" is good. Sometimes the drills will be fun, sometimes not. If you donít know good ones for you, ask the coach. Be very careful not to drill incorrectly. You might be emphasizing a stroke flaw rather than ingraining a correct technique. If you donít understand about how the drill should be done, or what its purpose, ask!
Our practices include drills. They are planned to emphasize and build in a certain way. If you do the workout as written with options discussed and approved, you will find that you improvement will steadily continue.