If your season has ended mate, then let them rest a bit, good walks every day is enough out of season, then prepare them a month before the start of the next season.
I like them to rest up a bit out of season and if that means putting a little weight on then so be it, no athlete can be at its peak 12 months of the year without it taking its toll.
I got stopped by a copper a couple of years ago doing same thing on a hardly used fell road, dogs seems good type, all the best. WR.
it doesnt really tire the dogs out its just really a change for them and mainly to harden the brindle ones