[GeoffAirey]

I can see the idea, but I wouldn't find it useful.

A single task / action is either 0% or 100% complete, there is no in between.

With projects, just because there are 10 actions to complete the project, this does not mean each is worth 10%, so you would then need to give each action an importance / weighting. and then what happens if you need to add another action in the middle you hadn't anticipated.

This would cause me more work than it resolves and I would class it as spending time tinkering with the system rather than doing actions.