Your first point simply isn't true. Search for Cromwell's comments on the lack of "adversarial debate" on the evidence (his polite term for lack of cross-examination).

Of course there would be a problem if they created absolute deadlines; that would have thrown the administration of justice into even greater disrepute. But the most serious issue is that the deadlines they picked are completely arbitrary. Cromwell also deals with this. If they were evidence-based, they wouldn't likely have fallen conveniently at round numbers like 18 and 30 months.