"are frequently" or "frequently are"

In this particular case, I'd say both usages are correct and mean the same thing. But as a general rule, it's safer to put the adverb before the verb it modifies. For example, if your sentence said that "the effects of change typically occur in a few places only", you could not use "concentrate typically" instead of "typically concentrate". Here it would sound unidiomatic; I could probably think of cases where it's grammatically wrong or gives the wrong idea.