I guess there are two questions in response. One, is everything getting done that should be? Two, what action is generating the question?
If everything is getting done, and done well, then the staffing level is adequate barring the answer to thesecond question.
If there are things on the horizon that will directly impact the required resource then it may/maynot remain adequeate, even though there seems to be much room in the time allocation.
My experience has been that the amount of time devoted to administration is most widely affected by the amount of change within an organization and the ability/failure to recognize the influence this has.
In a highly stable environment, little end user turnover and/or a mature set of applications, the level is often low. One caveat would be when processes or activities occur that are by nature admin intensive.
As an example, I encountered a full time person doing operations work which had been done routinely for years even though the business model had changed significantly downward. Process review showed that over 50% of the activity was no longer supported or was of questionable value. Thus reorganizing this effort achieved an administration reduction of 50%. Hardware and software and business growth changes can have similar impacts.
Likewise, where user turnover is high peaks can occur and a leveled view needs to be taken while allowing for the peaks.
Where there are process changes or new introductions there is a greater amount of time required as both processes have to be handled. This added impact should decline over time. Additionally, the manner of process change, planned versus spur of the moment, does directly impact the requirement for and allocation of resources.
In my opinion one of the primary considerations for staffing expectations is a realistic view of change impact to a going concern.