You can get from Berlin to Helsinki reliably by train and ferry in 2 days and 1 night (Berlin - Warszawa - Vilnius, night there, Vilnius - Tallinn - Helsinki)
But you cannot sensibly get from Lagos to Berlin in the same time, despite, oh, about 2000km of high speed infra to use
You *might* just do it with buses Lagos - Sevilla, and Barcelona - Perpignan, and the rest with trains, and a night in Perpignan
