I think all the different methods of swimming have some value but at the end of the day you need to find a style that suits you. By all means follow the TI or Swim Smooth techniques to teach you how to swim, but once you feel reasonably competent you need to develop a style that fits in with your own body mechanics and what you want to achieve.
There are different styles for sprinting (up to about 400m), long distance (up to about 5k) and endurance swimming. Also different techniques for pool, fresh water and salt water, and for wetsuit or non-wetsuit.
What I'm saying is take the principles but don't over analyse it. Some people get so caught up with getting the technique right that they never relax and actually learn how to enjoy swimming. When you relax it becomes natural and then you will swim faster while using less energy