The schedule is:
96 Depart: 3:15pm Arrive: 5:35am+1 757 Thursday
52 Depart: 5:30pm Arrive: 7:50am+1 A330 Daily
96 Depart: 11:05pm Arrive: 1:25pm+1 757 Monday, Tuesday, Friday Saturday
No 757 (second frequency) flight on Wednesday & Sunday
95 Depart: 7:05am Arrive: 10:35am 757 Friday
51 Depart: 19:55am Arrive: 1:50pm A330 Daily
95 Depart: 3:20pm Arrive: 6:40pm 757 Tuesday, Wednesday, Saturday Sunday
No 757 (second frequency) flight on Monday & Thursday
Actually those flight times make a lot of sense. The primary driver for the different timw on the Thursday DTW
& Friday FRA
is the desire to offer an early morning flight back. A lot of people on business want to get home in time for the weekend, and due to the flight times in the morning cannot get any meaningful business done in Europe and still get home at a decent time on Friday. So often you wrap up on Thursday and just get up and fly home on Friday. Makes more sense than a late afternoon departure on a Friday.
I used to do this when I was going back and forth to Europe for work for 3 months. I'd wrap up on Thursday, and take earliest flight back on Fridays, getting back into DTW
around 1pm. Granted, due to the jet lag, I'd be out for the night by 8pm upon my return, so it was be able to enjoy Friday afternoon back at home, opposed to wasting more of the day traveling.