Knowing how much time do we spend doing things is certainly a good information in order to plan our days in the most efficient way.
Of course, some days we might be more faster than others, and if we are on a hurry state 24/7 it might cause us to burnout.
Still, knowing the optimus balance between high speed work and sustainability (because let’s face we will eventually get tired) is a great way to maintain a high level of productivity throughout our week.