In my program, we had didactic lectures at 7 am Mon/Wed/Fri and 5 pm Tue/Thu where all the residents not on call must attend. Every hospital where we rotated had noon conferences which can be hot seats when the residents get grilled. Each subspecialty may have their own conferences and there were also physics lectures during certain times of the year. There were also monthly meetings at the city wide radiological society and visiting professors. The first years also had core lecture series.
Radiology training, unlike other specialties, does not have a lot of hierarchy. In large enough programs, the rotations are split into organ systems or by modalities such as Chest, GI, GU, Neuro, Pedi, Nuclear, US, CT, MRI, IR etc. Mostly only one resident was assigned to each monthly rotation. Each resident would eventually have rotated through each section several times, building on what had been learned. A junior level resident may have taken a rotation that a more senior level resident has not taken. In this way, the hours of the residents are very similar. The difference was what rotation that they are assigned to. IR hours are longer because the patients had to be worked and followed.