As I said before, I don’t think taking dex every other day would give the best control, I feel half the dose every day would be better.  Some people with CAH manage perfectly adequately on twice daily hydrocortisone  (taken 12 hourly), yet I believe 3-4 doses are better, due to the clearance rate already discussed.  However, those on less frequent doses of either hydrocortisone or dexamethasone are not going to go into an adrenal crisis because they are cortisol deficient for a few hours (especially if adults or patients with NCCAH).  I personally believe that for optimal control though, you should take dex once a day, as this will mimic normal circadian rhythm more closely.