Yes although you can individually set the worker rate in the conquests editor unit tab it well eventually also be dependant on the worker rate set in governments. It is a 2 fold thing. Personally I always felt that a work rate makes more sense lincked to a particular government rather than an individual civ.
Actually a three-fold thing (at least in C3C): In the units tab, WORKER RATE can be modified. From the on-line Helpless:
"Determines the worker strength of the selected unit. By default, the Worker Strength of each unit is "100". However, this value means nothing unless a unit has also been flagged with one or more "Worker/Engineer Actions", in which case that unit's Worker Strength value determines that worker's work rate. For instance, a worker with a Worker Strength of 100 performs his designated worker action at normal speed. If the Worker Strength value of a worker is set at "50" that worker works at "half" (50%) speed, and thus would take twice as long to perform a given task as a worker with a Worker Strength of 100; conversely, if the Worker Strength value of a worker is set at "200" that worker works at "double" (200%) speed, and thus would take only half as long to perform a given task as a worker with a Worker Strength of 100."
Best,
Oz