I agree ... there are several of us in this boat that wants to swim farther without stopping. The most consistent comments a couple of years ago spoke to "just doing it!" Without the dedication, which produces focused and goal oriented practices, we tend to become sloppy. When this happens we can become frustrated that years of practice have yielded little improvement. (Ignoring the requirement of dedication to the "cause".) I tend to think if and when I fix my breathing all else will flow better. However, as junkman points out, the aspect of being streamlined plays a huge part ... just as does being balanced.
A girl I see at a local pool who swims non-stop - length after length. I asked her secret. She says she feels she could go on all day because she constantly is breathing out. Hmmmmm ... we've all heard this before here. She isn't a TI disciple but she has the breathing down!
I'm headed for the pool in an hour and today will focus on being streamlined and breathing out more consistently -- and see if this helps. Nothing new ... but maybe more goal oriented this time.
If you're not swimming; then you should be skiing......