Swim drills are one of the most prescribed and least effective tools in triathlon training. Not because drills themselves are bad, but because of how most athletes use them. Done properly, drills can accelerate technique improvement dramatically. Done poorly, they are little more than a warm-up ritual that changes nothing.
The Two Problems With How Athletes Use Drills
The first problem is mindless execution. Athletes go through the motions of a drill without any specific intent. They do catch-up drill because the session says "200m drill" and catch-up is the one they know. There is no focus, no cue, no deliberate effort to change a movement pattern. The drill becomes a break from swimming rather than a tool for improvement.
The second problem is poor drill selection. Even when athletes bring intent to their drills, they often choose drills that have nothing to do with their actual stroke faults. If your problem is a dropped elbow during the catch, doing kick drills will not fix it. If your issue is poor body rotation, fingertip drag drill is not the answer.
Start With Footage, Not Drills
Before you prescribe yourself a single drill, get footage of your stroke. Have someone film you from above and from the side. Then compare what you see to stroke analysis videos available online. Unless you are already swimming under 1:30 per 100 metres, the faults will be obvious. And once you know what to fix, you can incorporate corrections into your main aerobic swim sets. You do not need a biomechanist to identify a crossover entry or a dropped elbow.
Once you know what is actually wrong, you can select a drill that targets that specific fault. This is the difference between drill work that produces results and drill work that fills time.
A drill without intent is just a slower, worse version of swimming. Know what you are fixing before you start.
The One Drill That Does Almost Everything
If I had to pick a single drill for triathletes, it would be single-arm freestyle with a snorkel. This combination is remarkably versatile because it allows you to isolate one arm while eliminating the distraction of breathing. A good centre-mount snorkel is essential for this drill.
With one arm at your side and the snorkel keeping your head stable, you can focus entirely on one element at a time: the entry angle, the catch position, the pull path, the release, the recovery. Each of these can be addressed individually within the same drill framework.
The snorkel is the critical addition. Without it, the breathing movement corrupts the drill and introduces compensations that mask the very problems you are trying to fix. With it, you get a clean, uninterrupted view of exactly what one arm is doing throughout the entire stroke cycle.
Do four to six lengths per arm, focusing on one specific element per set. Film yourself periodically to track whether the drill work is actually transferring into your full stroke. If it is not, you either need more time or a different approach to the same problem.