My policy as it applies to me is:
If I don't have a low enough gear, I get off and walk.
If I don't have a high enough gear, I coast.
But I believe in over-kill. I have an 11-32 cassette on my hybrid and recently switched to a 42/32/22 crankset because the 48/38/28 didn't get low enough for my bulk on a recent road ride.
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Slow Ride Cyclists of NEPA
People do not seem to realize that their opinion of the world is also a confession of character.
- Ralph Waldo Emerson