It is hilly once I leave the coast in my area.
So, on my training bike I have been using a compact (34X50) with the lowest gear at 34X30 from 34X28 a few years ago. I am converting this bike to 34X32 to ease-up on my knees as they get older. I am trying to aim at 60rpm on the steep sections. Now with the 34X30 I am at 54--60rpm.
On my other bike I use for racing (1 or 2 races a year now) and Brevets I have a 34X32 which I am increasing to 34X34. When you are tired you need a low gear to climb the steep sections. Some 200k Brevets have 3500-4000m ascent with extended climbs towards the end.
As I get older I have to use a lower gear to climb the same hills.
The important thing is to save yr knees.