I took the "expensive" bus to Shibuya at 10:50. I walked out of customs at 10:45. Had to walk half a mile after the MUC flight arrived, but immigration was empty as usual. Official arrival (probably gate, we had long taxi) was 10:30.

The bus arrived in Shibuya at 11:53. NEX takes 1 hour and 20 minutes and I would have waited extra 30 minutes in this case.....

The busy time of day at NRT T1 south is definitely around 4-5 pm when most US flights arrive.