I might work for 10-12-14 hours on end if I have clear instructions and if I am left alone to do my job. Under these conditions I am very effective, at least more effective than most people.
By left alone I don't mean being alone in the room (which would be preferable though) but, rather, without people asking me about things or having to participate in group work , discussions, etc. If I know what I have to do, I might very well motivate myself and keep the work going, but that's only until I know where am I going or if there's a tangible result I have to get to.
If not, I won't work as I don't know where to start. The latter depresses me a lot, as it seems that most people go to work to spend the day, talk to others and have coffee together - and do some work in between. I can't do all these things - if there's work to be done, I do it and might work very hard for days and weeks to get it done. If there isn't, I won't show up at all and rather spend the day with my favourite obsessions.
I am lucky that a lot of my work is done on a computer so I can work from home without wasting time in commutes and pointless dscussions with workmates. It is OK with my bosses so far as they know that when they have something really urgent or need work to be done late in the evening, on weekends of on Christmas (love it) they can count on me.