That's true because the cause of long covid has not been determined, or even if there is one "cause". For examples there was a sudy that showed some success with the drug Paxlovid which is also used for treatment of (initial) covid. Then you have read here and elsewhere that people have realized relief in approaching it as a central sensitization issue. The benefits from various approaches differ from great relief to very little and is why I'd like to know how clinics are being used as a means of not only gathering data and sharing, but if they will contribute to the focus of future studies and research, So you have the possibilities that long covid is the result of impact from the original infection, the non-detectable (continuing) presence of a part or aspect of the virus existing in the body, and/or the result of one's immune system going awry like an autoimmune disorder.

I've tried both, but not simultaneously...
I first tried a 5-day regimen of predniSONE (a corticosteroid)—it left me feeling MUCH worse. It took me weeks to get back to where i was before trying them (and months later my sleep is still worse).
I also tried a 5-day regimen of Ivermectin—it also made me feel worse (but not nearly as severe as I did post predniSONE).

I recently tried a 5-day course of Paxlovid—it didn't make me feel worse, but didn't make me feel any better, either...