Individual contributors would input a task or search-and-select from tasks already input by others. They would enter the relevant input variables (e.g. tools used, sizes, etc), and the time it took to complete the task. If there were complications that resulted in a longer-than-expected time-to-complete, then these could also be entered. Contributors could support these submissions with video evidence, and provide step-by-step instructions.
Ideally, the input data should be reduced to the simplest discrete elements of the task, so that it can be recomposed by the users of the data.
Users of the data would be able to access the fastest, slowest and average time to do a particular task. They could review the common complications reported. And it should be possible to have a tool to create a fully time-costed workflow by lining up a series of tasks.
With the right kind of description and categorisation, it should be possible to capture data on almost all human activity, but here are some examples to provide food for thought:
How long does it take to change a bike tyre?
How long does it take to hang out washing?
How long does it take to read a newspaper?
How long does it take to load a truck?
How long does it take to put together a piece of furniture?
How long does it take to register a sale on a cash register?