Controlling access to multiple systems

An anonymous reader writes: As an aging systems administrator working for a company over the years I have had to take on more and more systems and more staff, it is not becoming problematic to control access to systems with a 24 hour rotation of staff working from home and the office how would you go about controlling access into your systems, especially due to the nature of the work needing constant root access to fix little problems to big problems. Is secure and easy access for the right individuals really not a possibility? will something scale out to 100's and 1000's of servers?