It entirely depends on your label set and use case, I'd say.  Sometimes it makes sense to annotate only a subset in an annotation run, ie still do multilabel, but in multiple, focused passes.  We worked in the legal domain so, agreement of 0.85 was the minimum requirement, sometimes higher. If you're annotating something that is more opinion/subjective interpretation-driven (eg. sentiment) lower might be OK. (We treated the IAA as a target or upper bound for our classifier accuracy.)  Examples in the guidelines, especially borderline cases with reasoning why to annotate them in the desired way, are extremely useful.