I have never been married and would personally be very reluctant to involve a third party in conflicts and challenges with an intimate relationship. If communication is the issue or a main part of the issue, I imagine it can work some assuming that the couple also makes efforts to communicate differently in private. But if it is something like they are no longer interested in each-other and get much good out of the relationship, because it is just naturally over, I have hard time seeing how it could be saved by external interference. If they eventually divorce, maybe the counseling helps to accept that it is truly over and encourage people to make the steps to move on to a more satisfying life. Similar if the spouses just have very incompatible personalities, values and goals and there isn't anything actually wrong. People often keep holding onto dysfunctional relationships for many reasons and suffer in silence or just continue to live jaded. I think it can be useful to get some insight in those cases and realize it is perfectly natural and normal for relationships to end and needs/priorities to change. I think saving a bad marriage is as far from success and evolution as it can be.