I think I have had 2-3 fittings ever. My size didn’t change that much over the decades- went from A cup to B cup after having the 3 children and then up to a bigger band size and a C cup with the menopausal weight gain. After losing much of that menopausal weight (10 kg) I fitted into a favourite bra from before that and I still fit that one. I had several others of a particular brand which were pretty and fit well but those (they were a decade or more old) finally got tired looking this year and I went for another fitting with that same brand. The woman was very nice and seemed knowledgeable, she put me in 2 bras of that same size, one exactly the same style, and then said she wanted to try a different size. Like many of you, it’s a different band, one size bigger, and a different cup. I think I like that one the best but all 3 new bras have been worn a lot and are mostly good.
I was fairly astounded how long my bras lasted. I think about 12 years for those several? Not that I mind as they’re expensive. I look for a sale price if possible.