I needed to find a way to fly a single economy trip USA-Europe for less than $1,000. So, I am routed DCA-JFK-LHR-DUB-FRA with 2 segments on EI. But it was a cheap $300, but almost 7 hours more travel time. $50 more than EI USA-DUB-FRA, but I could not fathom an all EI economy trip.