Was E-6 and C-41 similar? I don't remember E-6 for transparancies.
When I first started I used to run E-4 for football slides for a television film chain. Best eight rolls shot, processed, cut, mounted, and delivered before 6:00 news. Water temp +1 or -0 degree was maintained starting before gametime (my old wife hated that). Four rolls of hand spooled (with latex gloves on) 36 exposure in a can. Ran two batches, 18 cans, at about a four minute stagger. Four of nine steps in total darkness timed to the second. If I remember correctly, 56 minutes in the soup.
Automatic after a while. I bet I could do it today.