In-depth article here: Using Lego[sic] to capture raw data for Cycle Time and Process Cycle Efficiency.
From the article:
The typical way to collect baseline numbers for these metrics is to conduct a value stream mapping workshop that involves most or all team members for one day or longer. The client is worried about losing too much time in the workshops when the teams could be doing value-add work. Therefore, we needed a less intrusive way to collect baseline measurements. There is also the question of how accurate the PCE data will be when it is obtained through a workshop rather than by direct observation of team activity.
I came up with the idea of using Lego bricks to collect the raw data for Cycle Time and PCE. There is some impact on team member time, but hopefully it is not too intrusive. My observation is that people enjoy manipulating Lego bricks, and they don’t mind sticking the bricks on a plate to represent their work.