Ignoring the plot device, it looks like Dany needs to start taking command since Tyrion’s strategies are sadly failing. So for now, she needs to take Olenna’s advice and start being a dragon, which means, she needs to burn the Lannister army and Euron’s fleet.
Also, she was the one who suggested to burn the enemies fleet, but they told her not to and what happens next? Her fleets gets destroyed once again.
I think that’s why you hear her saying: “No more clever plans” in the preview.