I'm an ultra runner and I haven't (personally) stretched in about ~5 seasons now.

I see a pilates/personal trainer once a week that basically does all of the items mentioned by the OP:

- hip alignment

- postural restoration

- stott pilates

- stretching

We target soas, hip flexors, glutes, hips, lower abs, etc.

Not a single injury since battling with piriformis syndromes and ITBS years ago. Life changing.