While also avoiding having to re-run cases to get new introspection when you forgot to add a print statement.

I tend to do both, print statements when I don't feel I want to be stepping through some cumbersome interplay of calls but diving into the debugger to step through the nitty gritty, even better when I can evaluate code in the debugger to understand the state of the data at precise points.

I don't think there's a better or worse version of doing it, you use the tool that is best for what introspection you need.