I believe it is estimated that the average menopause is between 5-7 years and this would be from the start of peri to when meno symptoms subside after post meno. Many of us will get flushes etc for 20 years or more. We are all different but I would definitely say that once your ovaries start to fail you are basically menopausal for the rest of your life. There will be the lucky few that have few if any flushes and generally have few meno symptoms, however, I don't believe any of us get off 'scot free', as vaginal atrophy, bone loss etc. will probably happen to every women. I do believe it has a lot to do with genetics although lifestyle will have an impact.
In my early 50s I stopped HRT due to all the scares and after 3 years there was no reduction in meno symptoms - so went back on HRT. Now 60, I have stopped systemic HRT (I do use local oestrogen for urogential atrophy) and now life is a little less stressful I am coping with meno symptoms better but I am not expecting these symptoms to subside in the near future.
In the ‘good old days' women were lucky to live long enough to experience the menopause, so one could think of it as a modern problem. In victorian times a menopausal women might end up in a asylum or hooked on laudanum. GPs are still dishing out the ADs/SRRIs for meno symptoms and this really has to stop unless depression is diagnosed.
DG x