And when the best sunrise/sunset light conditions last for 30 seconds, then what? I've seen plenty of times where that's all you get and something changes.
You should have your composition and everything set before the best light is happening. There is plenty of time during twilight to do so.
For landscape photos, I don't do a lot of fumbling changing lenses back and forth during that 30 second window. For a typical landscape, I would have decided that already decided to use my wider 16-35 zoom or my 50mm maybe 15-20 minutes before the sun goes down/up.




