Pixel dimensions describe how much image data a file contains; they do not describe the quality of every detail. Evaluate resolution alongside focus, motion, compression and the size of the final output.
Judge the file at a useful scale
Inspect fine detail at full size to find artefacts, then view the photograph at its intended display size. Excessive sharpening can make a small preview look crisp while creating visible edges in a print.
Keep a high-quality master and export separate versions for each destination. Avoid repeated resizing and compression of the only working copy.