A little of my history as a CAD Manager, that I think might answer your questions:
1998 - 2000 Part time CAD Manager - was given time only when absolutely needed and office was on fire
2000 - 2002 Part time CAD Manager at different company - 8 to 12 hours a week
2003 - 2004 Part time CAD Manager - 16 to 20 hours a week, as company (50-person , 25 CAD licenses) implemented Archicad office-wide, started building simple office object library & templates
2004 - 2005 Full time CAD Manager with added company/staff management responsibilities, responsible for staff performance and evaluation, who in turn were answerable to me on any graphic and production issues. Now we had SERIOUS objects and templates. Productivity went through the roof, since the entire object library had company-standard defaults and all questions got immediate answers.
Tom Waltz