There is one hill near us ... a fairly gradual one. I think it starts with about 2 km of maybe 5%, then flattens out to about 2% for a while, and then gets a bit steeper a km or so before it turns to gravel at about the 15 km point. Then we turn around and ride back down.

The first time I tried that hill, I was slow all the way up and struggling by the turnaround point. But we've ridden it a few times, and I've ridden a few other hills in the area, and the last time we tried it, I was a couple km/h faster and didn't find it a struggle at all. So I guess there is some improvement happening.