[mping]

Productivity is a function of concentration and understanding. If you have sufficient knowledge, what lacks is concentration. I'm perpetually amazed how people 1) fail to see this and 2) think their concentration power is fixed for life.

An example of this is when you do pair programming, your pair forces you to keep concentrated (and you force him too) - if you are screensharing you won't alt tab to reddit) so it's an example on how you can keep focused for longer periods than normal, at the expense of being more tired at the end of the day.