I find the same.  I tell my bosses I don't single task well.  I need to have multiple things to work on.  When I only have one thing to work on, and then run into an issue, I have to keep at it, because there's nothing else to work on.  The only breaks come with the end of the work day.  When I have multiple tasks and I run into a roadblock, I switch to another task while I mull the blockage in the back of my mind.  That time away is crucial for coming up with a solution without spinning my wheels.  Stepping away from a difficult issue, when that's possible, is highly recommended.