Our endo has always had us give the largest dose in the evening.  Although my son is currently on 25 mg a day 10 / 5 / 10.  So currently he gets the same both A.M & P.M.  This current dosage is the first time the A.M. & P.M have been the same.  She prefers the largest to be in the evening because she explained to me that the adrenal gland shuts itself down at around 3 am and that the larger dose helps get him through the night until his meds in the A.M.

As for stress dosing...... we have been advised to administer the total daily dose at each normally scheduled time during the day.  So for my son a current stress dosage would be 25 mg per dosage.

Hope this helps.

Judy