Terrib

I think it's more of risk reduction vs inconvenience issue. IMO, it's not worth the risk of losing my teeth over using a flouride tray since I've seen zero studies suggesting it would be safe to quit using them..
A quick search turned up that the National Cancer Institute at NIH recommends daily use of fluoride trays until such time as full saliva returns. There were some studies on oral cancer patients purporting to show that patients who skipped fluoride trays got cavities and some lost their teeth. But they were not clinical trials, double blind or anything so not proof positive (or else I'd have linked to one of them). If a dental college web site or dental hygienist web site mentioned it,they advocated daily use for life for head and neck cancer patients who had received radiation.
But who knows, maybe three times a week is plenty, it's just that your post is the very first one I've seen since joining OCF that does not say their dentist or RO told them daily use.
Hey, you can let us know in a few years how 3x worked out for your husband
Charm