You learn both ways, the degree definitely depends on the program. For example, U NC gives daily lectures to residents for 30 minutes in the morning. Other places have lecture once a week attached to grand rounds. Some attendings will stay in the OR with you and discuss topics. Others are there for induction and extubation and not much in between. Most programs have attendings at both ends of the spectrum. A common theme I found at programs when I interviewed was that how much teaching you get in the OR depends on your level on interest. I experienced this on my anesthesia rotation as well.
Spouse of EMdoc