The only real problem with that timetable layout is that the aircraft is sitting around on the ground from about 8pm, thats not good for Ryanair, Thats why this alternitive might just work around that problem
BLK - STN 07:00 - 07:55
STN - BLK 08:25 - 09:20
BLK - GRO 09:45 - 13:00
GRO - BLK 13:25 - 14:50
BLK - DUB 16:10 - 16:55
DUB - BLK 17:25 - 18:15
BLK - STN 18:40 - 19:35
STN - BLK 20:05 - 21:05
As some people might agree this timetable is better, Yes there is a 1hr 20min crew change period, however Ryanair have these times of crew changing periods through out there base areas.
And also the aircraft gets onto the ground at 21:05 insted of 19:55, quite a big money making difference. Have Ryanair ever considered Shannon From Blackpool?