[dmaharding]

For how that might work (or not) in practice, you might want to check out Vermont, which has had many years an extra transfer tax on land held fewer than 6 years. https://tax.vermont.gov/sites/tax/files/documents/LGT-178%20...

The table of rates on page 6 says they'll charge up to 80% of your gain on land held less than 4 months. It doesn't seem to cover improvements, though, so it's anti-land flipping tax not an anti-house flipping tax AFAICT.