I'm in Brazil and right after I signed up for a new number, I was getting 15 spam calls per day, everyday. They recycle numbers here so some of those were "legit" but meant for previous owners. As an American with a US number too, the difference is night and day. My US number gets 1-2 spam calls per week or per two weeks.

But yeah, I do the same. All set to auto ignore, even though it means one or two necessary calls are missed (ex. my cc company wanted to inform me they were cancelling their partnership and thus closing all cards).