In an ideal world, yes, especially if requirements/scope/environments change. But the world is often not ideal. Often unless there is what they see as good reas

In an ideal world, yes, especially if requirements/scope/environments change. But the world is often not ideal. Often unless there is what they see as good reason (the definition of good may vary widely), managers & business planners don't like estimates going up in the short/medium term and pressure to try stick to the original estimate may happen.