You can't coast into being a good radiologist. Radiology is very broad and residency requires a significant amount of studying compared to other specialties.
The radiology workday might be 8 AM - 5 PM, but it is mentally exhausting work. If you read images on cruise control, you will miss findings, some which may be important. Radiology requires constant/intense visual and mental focus. Call is very busy and volumes are usually high. I was more fatigued post-radiology call than almost every call shift in my internal medicine year.
That said, I enjoy radiology. I chose it over internal medicine and I have no regrets. I love the subject matter of internal medicine, but was not a fan of the social work, documentation, rounding, mental masturbation, endless clinic and sometimes difficult/non-adherent patients. I figured it would get routine and boring quickly. I also do not need patient interaction to feel good about my work.
Radiologists do make imaging diagnosis. The problem these days is that imaging is abused/over-utilized, especially for pathologies that can be diagnosed clinically. For example, a patient has no fever, no flank pain, normal BMP and a normal urinalysis, why request a CT abdomen or renal ultrasound to rule out pyelonephritis which is itself a clinical diagnosis? Why request a CT angiogram runoff of the lower extremities because of pain with walking when an ABI or PVR has not been performed, and instead the patient's complaints are due to knee osteoarthritis? This tends to be more of an issue with NPs and PAs, but it is getting worse amongst our MD/DO colleagues.