oh those shiny objects. they get me every time.
this sometimes works for me. i work on two projects at the same time. i have both on my work table in separate piles. i work some on the first pile, and then switch to the second. i go back and forth between both until one is done and ready to be sandwiched. then i try to get that far with the other. if i get bored before it's done, i haul out another WIP and switch between those two.
it satisfies my short attention span and things get done by about the same time they would have if i'd worked all the way through one before starting another.
doesn't always work, but it does help sometimes.