What I was trying to say earlier is that productivity blocker is your process of dealing with uncertainty. It's easy to ignore things that you have little knowledge on how to execute until it's too late and can cause massive fuckups in the thing that you are trying to be productive on. It is also easy to purposefully ignore an uncertain process because it causes too much anxiety or stress. Personally I have had to deal with both of these situations so many times.

In the first instance, an example including myself. I was in first year uni doing an engineering unit involving a team project, one of my roles in the team was to do cad drawings of this thing we were designing. The drawings were a major part of the final presentation. I was the only one experienced in a drawing program but I wasn't really what I had to do to draw the design. Long story short I left it to the last week and spent about 3 nights working until 3am trying to get drawings out that were half decent. If I had spent some time earlier in the semester working out how I could do the drawings and what processes I would need to do the stuff I could've done the drawings in an afternoon.

When there are processes that you don't know how to execute, figuring out how to execute them and stabilising ( the process does the same thing every time ) them is a good way to become more productive.