The people who will perform the task are the ones who can best advise the designers. Unfortunately, it often seems that our planning process does not take into account the time needed for adequate front-line input. Too often, for reasons of time or expediency, we use proxies. Simply having once worked the ranges or in the file room does not qualify a manager to assess the adequacy of the design for the performance of those tasks today - too much has changed. Inmates are different.
Procedures are different.
Even legislation is different. Our planning process often fails to recognize that front-line people cannot respond to proposals as quickly as staff who work at some other levels. As well, many front-line people work shifts. Managers may be accustomed to making linkages quickly between concepts and assumptions that are part of their daily currency. Those items are not the daily currency of front-line staff.