After 15 years of usage it's no theory. If others deny or insult then why publish? Either accept and try or keep boosting the profits of the varoa strip manufacturers.
Always when autumn feeding, spring (this week all hives treated) and occasionally throughout the honey season if there is no nectar arriving.
I think what you need to do is stop responding to the naysayers ... if you don't respond they will give up
I don't treat my bees for varroa... I haven't done for 10 years ... what I do works for me in my location. I don't try to convince others that my methods work although I know they do. I'm largely in the same boat as you - I'm delighted that the method you have described works for you and I'm sure there are a few open minds who may try it - the problem you may face on here is that you are, currently, in a minority of one - nobody else (and I've been on here a good few years) to my knowledge has ever suggested sea salt as a varroacide. It's a public forum, lightly moderated but you can expect people to call a spade a spade so a slightly thick skin is needed if you bring something contentious or otherwise untried to the forum.
I use dowsing to site my beehives on lines of energy - the forum erupts whenever it is mentioned with those who don't accept seeking to find every reason known to dispute that dowsing is legtimate. Do I care ? Not a lot - it works for me ... anyone can try it but I'm not suggesting they have to.
I accept that you have had success and I would hope that other forum members will also accept that, in your case, your location, your hives and your bees it has worked for you. Tell us a bit more about your beekeeping, what hives you use, how you husband your bees generally and you may find, like me, that your methods are accepted alongside your ability as a beekeeper. If people follow your path, that's fine.., if they don't- well the way for you to look at it is that it is their loss.
This forum is a wonderfully diverse place, there are all sorts of ideas, knowledge and innovations being continually discussed - some good, some not so good. Join in, widen your posts to other threads and with the number of years you have kept bees I feel sure you must have some good advice to offer those who arrive here with less experience (and often in some difficulty).