Once you start investigating workflows from the point of view of the work-items instead of from the workers perspective interesting things start to show. One tool to do this is the "value stream analysis" – one of the tools in the lean approach.
One of the fascinating things that came up again when Tom did that in a simulation at the Agile BI-Conference in December '13 was this same fact, that is often the root-cause of a certain kind of workplace unhappiness: the difference between the idle-time of the person doing the job (nearly no idle time at all) and the idle-time of the ‘item under construction’ – or product – which might easily approach or even exceed 80%.
If we take one requirement as the work item and map out its way through two weeks of development in a simple two-state graph we see that there are only small peaks of work while the work-item itself is idle most of the time.
The workers on the other hand – who try to fit as many requirements as possible in their time-box – are always in a busy state!
So, if it takes forty days to deliver a net worth of one workday it is no wonder that perceptions of workload might differ 'a bit' depending on your vantage point.
After all: however busy I may feel, as soon as I try to do five things in parallel, this also means that whenever I work on one of them, four of them must lie around idling. Totaling an average of 80% idle-time per Item. When I think about this it makes me want to introduce more measures to limit my work in progress every time!
So, have a good time mapping out the value-streams of the work-items that are most important to you – you never know what you might find out.