I suppose if you asked a professional athelete or an artist whether their craft had become 'routine', nearly all would answer in the affirmative. If you asked whether they continued to love their pursuit and want to immerse themselves in it, most would also readily and fullheartedly agree.
Bored people are...boring...no matter what they're doing. Some people devote themselves to refining and promoting all the stages and changes of a lifelong relationship with one person. Others hop from one person to the next, going through the same initial stages of a relationship over and over again, but with continually new people. There is not one correct way to be, nor one path which satisfies each personality type. And what may feel right in one stage of one's life may not in yet another.
Will surgery, or any discipline of medicine, continue to have that butterflies thrill of a new experience? Not likely. And that's true of virtually all experiences in life (including research). Whether you will continue to grow as a clincian, a medical detective, a community leader, a professional colleague, friend and teacher, and - especially - an artisan, will depend a great deal more on what you are like, rather than what the field of surgery is like.
Stepping off my soapbox now...
