When you water, do you pour it through and call it done? Or, do you fill a basin/bucket and let the plant drink from it for a while?
The watering frequency sounds to me too like a little much. These plants can store water, so, a bucket soak can do 2 things: Revive a thirsty one that has used up its stores, and, allow the roots to dry well between waterings so root-rot won't happen.
Root-rot shows the same symptoms as underwatering. The reason is that dead roots can't convey any water up to the plant, even if they are constantly wet from frequent watering.
So it sounds like you have already checked your root health and took care of some rot. I don't know how long ago that was, or whether you've done the same recently for (I think you said) other ones that also are wilty. But once they are free of rotted roots, the new watering habit would be as described in
this post.
If you water this way, it won't matter as much whether your medium is holding as much water as well-soaked bark would.
It doesn't sound to me like your problems are from feeding wrongly.
Good luck,
BL