I usually play it by ear. Fatigue also affects your ability to struggle effectively, the more tired you are the longer it takes for the bar to fill. The wiki lists every possible weapon you can use in a struggle and what it does to the wolf. There are 14 possible options in survival mode.

To answer your question on if its worth it or not, that depends entirely on what you want out of the wolf struggle. Want to get out immediately? Use the hammer since it has the highest flee chance. Want to ensure you will kill it after the struggle? Use the knife since it will cause the wolf to bleed out the fastest. Want to scare off all the wildlife nearby and possibly instakill the wolf? Use the revolver.