The lesson? Always keep copies of your images in layers. That way, if you need too add or subtract something later, you can without rebuilding your entire graphic.
Keep Those Layers
But had I saved the image flattened like that, I would not have been able to go in and adjust the cloud layer after I decided it was too dark and made the text difficult to read. So, even if you think you've fixed the image, still keep a layered version around in case you need/want to tweak something later.
The Versatility of Layered Images
I certainly flatten images to bring them into my NLE, but I keep a copy with the layers just in case.
Your Media Production Mentor