Sometimes we need to be persistent in our research--like the dog that just won't let go of a bone.
However there is a flip side to that--when the dog refuses to let me trim off those little mats of hair she gets. Sometimes there my be an idea or an assumption that is near and dear to us, but is in the best interest of our research to let go.
It's fine to go at your research like a dog goes after a bone. Just don't hold on tightly to things that you really need to slough off.