Yes, when looking back at all the data gathered over the last 25 years, it seems that patients with whiplash injuries and whiplash-associated disorders (WAD) have better results with minimal treatment.
Sometimes a few sessions with a chiropractor or physical therapist for manual therapy (joint manipulation or mobilization) is effective. For both WAD and nontraumatic neck disorders, supervised exercise (with or without manual therapy) is another possible option that seems to work better than no care.
But most of the studies show that the best strategy of care for WAD is indeed less is more. Too much treatment too soon seems to interfere with healing and prolongs recovery.
And there's no evidence that treatment (of any kind or in any combination) for more than six to eight weeks is going to help improve the patient's condition. Follow your doctor's advice but keep your follow-up appointment if your symptoms don't resolve. You may be a good candidate for a short course of manual therapy if things don't turn around for you.