Previously, the clock in our kitchen was three minutes fast, but now is about 6 minutes fast. And what a difference the extra three minutes makes. We don’t believe the time anymore. Our brains have switched from ‘it’s time to go’ to ‘the clock’s fast’. The difference has become too great to be believable. And the intended goal of getting the kids to school on time in the morning is lost we look to other clocks for the ‘actual’ time.
Providing a vision (big or small) is a bit like this. We need to stretch people’s views of what is, but it needs to believable. Otherwise we’ll look elsewhere for the ‘real’ vision.