I don't understand your "We had a Problem" portion of the question.
I'm kinda of guessing even at the first part but it sounds like you want a count of times an employee worked in a set time window, irrespective of shift and an average of shifts worked by employee for that same time frame?
Im sure my assumptions are off on some level but if you can go into more detail about what is needed I'm quite confident it can be done.
See the attached: Includes the parameter to select a number of days to evaluate. There's a T/F calc field that uses that parameter value to determine if a date is within Parameter number of days ago. (Anchored on 3/1/2014 but in real world should be anchored on Today() ).
The sub total for each job type is totaled using Average, so it tells you how many shifts were worked on average by those employees during that time. I also didn't follow your question, so I'm guessing here also.
Hope there's something useful there.
Date Tester_v2.twbx 36.8 KB