Important thought
Following a time discipline is very important: I have been neglecting this for a very long time now. Fixing a duration of time for types of activity will definitely help. From my observation, spending more time on a task than needed has two affects. First, after a specified duration productivity and duration are not related and most of the time it is just complete waste of time. Second, right brain will not be exercised: the ability to correctly evaluate “why” you are doing the task will be affected.
Taking a break has always allowed me to be more effective - doing the right thing, rather than being efficient - doing the task well but not be needed at all. Taking breaks has allowed me to have a general perspective and clarity - and several times I am rewarded with incredibly helpful insights.
Additionally, taking breaks will refill my brain stamina to resume the task with more focus and energy.