Currently, JMeter either retrieves embedded resources or not.  If retrieving, 
it will keep on retrieving if the request is issued again.  This does not 
simulate a real-life scenario.  What JMeter needs is a browser cache behavior. 
Each request should be set to retrieve all embedded resources and Jmeter should 
keep track for each thread if a request for a resource has been made or not. If 
so, do not request again. That is if the headers do not indicate no cache.

For example, the test plan below.  On the first loop, the second HTTP Request B 
resources should not be requested again.  And of course on the 2 to 5th loops, 
all requests' resources should not be retrieved again.

Test Plan
      Thread Group
           HTTP Cookie Manager
           Loop Controller - 5 times
                Simple Controller 1
                    HTTP Request A (Retrieve all embedded resources)
                    HTTP Request B (Retrieve all embedded resources)
                    
                Simple Controller 2
                    HTTP Request C (Retrieve all embedded resources)
                    HTTP Request D (Retrieve all embedded resources)
                    HTTP Request B (Retrieve all embedded resources)