Proper marathon training should always be planned in advance and well thought-out.
My training on the other hand... needs more scheduling! On Sat I wanted to do 24km, but my body was screaming no. So I turned back and ran home, just above 15km. I was sooo tired. In hindsight, it all made sense to me: during the week I had run 3 times above 20km with one speed session, and one time 15km. Of course I was tired! I took it easy, and in the evening I biked 25km. On Sun I was well-rested, so I did: 20km, of which 5km between the third and the eighth km were tempo. In the evening I did 10km easy run. Total for last week:122km.
This week I would like to do 110-115km, with one long run and possibly one speed or tempo session. Only five weeks for Berlin, I believe at this point rest and listening to your body is key. I am definitely keeping away from overtraining!