Africa of course already has 3 regional currency unions (West CFA, Central CFA, Common Monetary Area) and I wonder if that would have worked better in Europe as

Africa of course already has 3 regional currency unions (West CFA, Central CFA, Common Monetary Area) and I wonder if that would have worked better in Europe as well. Call it an intermediate step if you want, with the united Euro a kind of nice ideal to strive towards, once all EU economies are on the same footing and have well-correlated economic cycles (so basically a long long time in the future).