I went far to easy on my 172 and it never paid me back for it. The 182 was still run in only not as sofly softly and it goes just how it should.
The 172 I kept it below 3.5k for 625 miles then upped it a little until at 1000 miles I was driving normally.
The 182 I kept it below 3.5k most the time up to 100 miles, then started upping it, by 625 I was back to normal driving.
Having run two of my cars in far too softly and one not quite as softly I can certainly notice a difference. Unless two of the cars were just had examples. What Edde says makes perfect mechanical sense though.
Whatever you do, make sure its fully warmed up first.
What Omar said about a constand speed is supposed to be a bad way to run an engine in, it needs variation but not caning or excesive labouring.