Long resistance running

I have always used hills and sleds to develop power, tehc and acceleraton mechanichs, never excedding 40m, usually using 20 -30m.
After re-reading the whole KK system, and remebering what my coach used to do whn i was a kid, I’d like to discuss the role in preparation that long hills or 80-100 m sled runs can have.
In italy some 400m specialists used 60-80m sled runs, more with a power endurance emphasis I?d bet.
For long hills can be the same?never used them for more than 80 in the past, and now I run and coach using them for other purposes.
Thoughts?

concerning longer sled runs:
since we achieve an upright position after 40 or so meters, using the sled for 80 can be used as a "special " exercise.
However, since the resistance is towed, can it lead to a more pawing like action instead of a vertical one?