“Lydiard (and others) specifically has them in base – alternating flat, easy days with rolling hills, slightly harder effort, iirc – but all aerobic in base.”
….those aren't just rolling hills…trust me…..they are “smack u into the ground and make u want to quit running sorta 'rolling hills'”…..
I may have erred in my wording and some adjectives, and I can't, for the life of me, find it in “Running to the Top”, where I'm sure I saw it. He may have just said “hilly”. But to me, “rolling” implies multiple ups and downs so you can just keep running. No need to for directional reversals at top or bottom. IOW, you learn to run hills, not just do repeats. Unless somewhat specifically says “gently rolling” or provides some other descriptors, I try not to assume anything about the size or steepness of hills.;) “Hill” means very different things to road, trail, or mountain runners. And some of the ultras with 10-50,000 ft of up and down could be considered “rolling hills.”
I've looked for a good description of some of those NZ routes, but haven't found much – just that the one is 22 mi, but I don't think I ever found how much elevation change is in there or how steep the hills are. I know NZ has some good size hills (aka mountains) since Jonathan Wyatt and Melissa Moon have done quite well in mtn races on international circuit.
But, bottom line for the OP, is that some programs put the emphasis on just running a diversity of things, alternating terrain and effort. If he doesn't have any flat, then running gentler hills on some days may be good while he's building base. Make the best use of the terrain a person has and adjust training to suit it.