Something that we have been stung on in the past, and I know a few other people in the APAC group have as well, relates to the 'All' checkbox within Canvas Commons.
I personally think that the confusion caused by this feature is multi-part. The first of which relates to Enable contextual (Course) view in Canvas Commons. This (however) is the second part.
Aside from the confusion caused by a lack of context, after the 'All' option is selected, you may note that the 'Import into Course' button does not change. It still refers to a single course.
We have had several occurrences of people importing across all the courses in which they are a teacher, which is a dangerous prospect for administrators and learning designers alike, who may have a teacher role in many courses (for a variety of reasons). Whether you are an admin (like me) or a teacher/faculty administrator or other, you may have run across this yourself.
I have had a few thoughts myself, all really surrounding something that is far more prominent. At a minimum, I would like to see the button change so it specifically states 'Import into ALL courses' (or a truer statement) 'Import into ALL courses which I am a teacher'.
Some other ideas that have been proposed in the APAC group (where we first started pondering this) was to have a 'warning popup' to ask 'Are you REALLY sure this is what you intended, you are going to import the content into a large number of courses'.
To ask a broader question, do (m)any people have a necessary use case for having the ability to import en-masse to more than one course?
Would love to hear everyone's thoughts, would love to see something done to make this a little more user friendly and protect us from ourselves (hey, I have been there, I have checked the box, and I have had to do the cleanup... so it can happen to any of us).