Possibly one for a doctor to answer, but surely it would depend on the condition, the medication taken, his job etc. Without knowing specifics on any case (and having no medical knowledge) it would be difficult to say. But in theory if the medication had no adverse affects on the person and if forgetting to take the medication would not cause major problems then I can't see any big reason for an MD. It would also depend on the job I pressume.
You have to hope the Docs know what they are doing.