Lonely, fast running on the road is boring, but lonely, fast running in the park with o-map is exciting! (even if I know the area of the park). Full speed 8x3' (with 3' brake) was good for: exercise of speed up in short time after the start (I always have problem with this thing on the sprint competition) and changing speed during the race (reading the map-middle speed; only running-full speed).
In April I did 32hour of training . In this running 19h, orienteering 8h and other activities 5h.