I use the same "thinking" as Kfergos, probably because we live in the same area.
Every ride I do from my house includes a 10-15% grade short climb to get home. My regular loop rides all include small hills that are medium steep (but short). There is only one ride that I classify as "flat" that I do out of my door.
What I have found is that what some people call rolling, I call hilly, but they are short rollers that are 5-6%. It's just that there's a lot of those around here.
I have done rides with 4-6 thousand feet of climbing that usually involve very steep climbs that are short, but come one right after the other. Those are "very hilly" to me.
Unlike others here, I liberally use my granny gear and last summer I saw 4 mph on Mudgett Hill Rd. in Charlton, MA. It was about 1.5 miles, with some spots at 18-20%. I don't care how slow I go, my goal is to get up the hill. I have only walked once, and that also occurred last summer, in Blanford, MA. It was about 1/2 a mile of 15-20% grades, which then crested, so I got back on my bike. Of course, then there was about 2 miles of 10-15% climbing, but I did that one..