Each treatment probably worked at least once, in some cases because it was used just before the cat was going to get better anyway. Some of the treatments do more harm than good. Male cats with urinary tract disease often get plugged up so they can't pee. This is an emergency and is fatal if not treated. One of the many special cat foods may help prevent the plugging up but will probably not prevent idiopathic cystitis.
Women also get idiopathic cystitis and the human disease is also frustrating to treat.
There is an antidepressant drug called amitryptiline that is used in Parkinson's disease and other conditions. Doctors noticed that in some women who were being treated with amitriptyline, and who also happened to have idiopathic cystitis, the cystitis cleared up. No similar studies have been done in cats, but the drug is commonly used by veterinarians in cats and sometimes seems to be effective. If your cat starts peeing where you'd rather he didn't, he needs a checkup. It may be something simple and curable.