I was watching a Summer Rayne Oakes video where she said that once you have pests, it’s pretty much impossible to 100% eradicate them.
If you only have a few plants that’s maybe not the case, but I have… a lot.
It actually really helped my mindset, because now I’m much more diligent about dusting leaves, keeping an eye out for damage, and not panicking.
I have a Calathea that has spider mites atm, and it’s doing ok. Rather than spraying bug killer all the time, I just moved it into my bedroom (where it can be in quarantine) and I shower it and wipe the leaves down regularly. The mites keep coming back, but in smaller numbers each time.