Back in the 1980s I did London to Thessaloniki (and vice-versa) by Magic Bus - later it became Eurolines - seven times, totalling two-and-a-half weeks on a bus, each trip lasting 62 hours, i.e. two-and-a-half days. I realised that that was getting to be too much when I recognised specific houses on the outskirts of Belgrade... The German buses from the UK to a German city, either Frankfurt, Stuttgart or Munich, were great. Then you got off and onto a Greek rustbucket.