My experience has been that when it is serious, one gets the news back quickly (e.g, a call from the hospital is not a good thing!).
Some clinics – e.g., breast cancer in Ottawa – have a best practice when the imaging oncologist sees the patient within about an hour of imaging to be able to give a quick interpretation. Reduces the waiting anxiety to almost nothing.
Having read my full share of imaging reports, as well as having seen my own scans, I actually prefer having the professional interpretation – even if I have to wait a bit.