Working on power will benefit almost all competitive swimmers from sprinter to endurance, pool to open water.
This is because, even if you swim endurance events, the stronger and more powerful you are, the more able you become to stretch your capacity beyond your natural pace. In short, if you want to swim fast, this is a must train element of fitness.
The principles here are very fast efforts of 20-40 secs with long 90secs-3mins recovery (pretty much complete) between reps.
As always you need to hold a good technique. Beyond that, just go ahead and swork as hard and fast as you can. Make sure to feel fatigue in the correct swim muscles (particularly the lats) and remember that this is most stressful type of training, so you need to make sure you’ve got good base conditioning.