Historically, the US has had 27 amendments in 225 years, which is basically “one every decade or so”. Even if you aggregate the whole Bill of Rights into one, 18 in 225 is every 12.5 years. They’re in a bit of a lull now(though only 20 years), but they’ve done a dozen in the last century. The cutoff seems to be set at precisely the level that stops idiocy like anti-flag-burning and anti-gay-marriage amendments from passing, which is to my mind a good level.
Historically, the US has had 27 amendments in 225 years, which is basically “one every decade or so”. Even if you aggregate the whole Bill of Rights into one, 18 in 225 is every 12.5 years. They’re in a bit of a lull now(though only 20 years), but they’ve done a dozen in the last century. The cutoff seems to be set at precisely the level that stops idiocy like anti-flag-burning and anti-gay-marriage amendments from passing, which is to my mind a good level.