I see project after project take longer than it should and have a considerably more complex design phase than is necessary. This is often, but not always, down to a combination of poorly defined and / or changing requirements.
Things change, but this should be in a controlled manner. For anyone working in the architecture, solutions, or indeed development space do yourselves a favour and try not to start detailed design and development work until the requirements are clearly defined, understood, signed off and change controlled.
This will make your life a lot easier and actually lead to solutions that better meet the needs of your business as the requirement(s) will be well thought out and clearly defined.
Challenge the requirements! Along with ensuring requirements are clearly defined, challenge them, are they genuine requirements, do they clearly meet business / regulatory etc. needs, are they requirements or ‘nice to haves’.
All designs should be requirements led; Solid requirements enable the right solutions.