Hi Gin,
In the practice of asana, the physical practice which is part of yoga, strengthening comes only after alignment. It would be an exceptional case where a student, fostering imbalance, strengthened before aligning and came away with a more balanced musculo-skeletal structure. Ergo I’d suggest an alignment-based practice where the teacher knows and employs this principle in their teaching. Unfortunately sound teachers are becoming tougher to find as teacher trainings become more prolific and those who offer them slip on the slope of integrity.
If you can find a compassionate Iyengar teacher you can be well served in this regard. Viniyoga, Purna Yoga™ (in which I practice and teach), and perhaps Anusara could all be helpful.
The frequency of a therapeutic asana practice depends on the practice, the practitioner, the issues being addressed, the other things one is doing in their living, and the results. Five variables make it impossible to give you one answer. Start slowly and set reasonable expectations for yourself and the practice, then grow it from there.
Anyone who’s practiced for any length of time has had similar issues. What I’ve learned in my practice is that as long as I am unwilling to alter the behavior which is creating the issue, complete resolution is problematic. Of course just sitting and taking it isn’t profound either. So doing the best we can AND looking at our choices helps us live more joyfully.
gordon