Bad Medium, Good Intentions

[AaronM]

Hi all,
I work in a garden center where they sell those mass produced Phals. I have been doing my best to keep down the orchid mortality rate, but I am having trouble figuring out how much to water all the Phals. that are in nasty, rotted, old medium with the texture of used coffee grounds.
These poor things have a bad habit of rotting at the roots and I have to try to keep them looking nice so they can all find good homes before they get past the point of no return. I make sure to tell anyone I sell these orchids to that they must be repotted as soon as they drop their last flower.
Should I only water these orchids when the medium is completely dry? Keep in mind that may take them a couple of weeks after a watering.
Also I was thinking of moving all the bad medium orchids to the outer edge of the display so they get better air flow. Do you think this might help?
Keep in mind I have some major limitations. First I can't repot them. Second anything I do for these plants needs to take minimal time or I get in trouble. Third I've taken responsibility for these orchids so they need to keep their flowers and sell or I get in trouble.
Lastly, some of the orchids are actually potted in fresh coconut husk chunks. Is this an acceptable medium or should these plants also be repotted after they finish flowering.

Thanks for any help you can give me with this dilemma.
Even an overproduced box store orchid is a terrible thing to waste.

AaronM