Thank you for providing your perspective. Research has shown resitance training can be just as effective as strengthening for improving rangs of motion.

https://medium.com/better-humans/stretching-or-resistance-training-which-is-better-for-flexibility-c292107341eb

As for the combination question, that has not be researched. It is possible that long duration, agressive stretching mimics the tension produced by resistance training. A combination of resistance training with 1 hour of agressive stretching may overtrain the muscle. It may lead to diminishing returns and not be worth the time dedicated. I think stretching can be useful in some circumstances, but it is not necessary for improving mobility.