But I will argue that knowing complete product requirements up front is a quite rare exception, not the norm.
System debugging has always been a graveyard-shift occupation, like astronomy.
The management question, therefore, is not whether to build a pilot system and throw it away. You will do that. Hence plan to throw one away; you will, anyhow.
Present to inform, not to impress. If you inform, you will impress.
How does a project get to be a year behind schedule? One day at a time.
Software work is the most complex that humanity has ever undertaken.