Just as a personal preference i'd like to see how many items go in and out of my containers. As probably anyone else, i use them as buffers and it's kinda hard to see if the input can keep up with the input over a longer period of time.
A sliding window average saying "last 5min rate: in: 102 i/s, out: 103 i/s" would suggest that you wont be able to keep up with the demand of the things pulling things out of the container i.e. producer/consumer. Similar to the performance indicator on the machines.