| You are correct. 6 hours including the breaks. I am an employee at a large distribution company for IT hard and software. I think there are many factors that play into how long a productive day really is: Type of work - is your job requiring brainwork all the time or maybe you have some work in-between that just requires execution prime to thinking work? Environment - how good are you shielded from distractions? Communication - do you really need to be shielded? Maybe you need a steady communication to proceed with your work. I'm thinking about the guys at stock market e.g. Type of breaks - This is a big one and up to personal preference to a degree. Are you forced to take a break? Is it a hard force or a soft force (telephone vs. mail).
Do you have to respond immediately? A big problem for me e.g. is interruptions when i'm in the middle of it. It takes a fair amount of time to get back into the zone. If this happens i often like to refer to this article: http://blog.ninlabs.com/2013/01/programmer-interrupted/
It's hard for people to understand why interruptions can be very harmful for work. So if i say 6 hours, this is the maximum for me to work concentrated on one topic. Interruptions diminish this number, shorten my concentration timespan and often make the day not as productive (subjectively). edit: formatting |