I've heard about a kilometer. This isn't super daunting though. As long as you can get it down to two steps or one steps then you'll be fine. Usually, it's getting out of 3 steps that's the hardest part about these hunts. Everything else from there is much better.
I thought it was about 1km too, but tonight I had a 3 foot Rhyhorn pop up on my radar. Went about a block and there it was. Quarter of a mile, tops (So more like .5 km).