Here are all the routes that are up to 2 hours in the timepass:
ORGN DEST BLOCK R/T
FRA LUX 01:25
FRA BSL 01:45
MUC GRZ 01:45
MUC PRG 01:45
MUC ZRH 01:50
MUC TRS 01:50
FRA BRU 01:55
MUC BSL 01:55
MUC VIE 01:55
FRA ZRH 02:00
total: 18:05
As you can see, it's fairly annoyingly just over 18 hours.
For 6 hours, you can get 6 segments, 9 hours 10 segments, 12 hours 12 segments. 18 hours wuold have almost been 20 segments, but is 18.
The weird utilization is because of what is left over.
As for price, it works out 41.50 per segment / 37.90 per segment / 27.72 per segment for 6/9/12. The extra 5 minutes put 18 hour option at 41.55 per segment.