Taking time away from something and then returning to it later often reveals flaws otherwise unseen. I’ve been thinking about how to gain the same benefit without needing to take time away.
Changing perspective is the obvious approach.
In art and design, flipping a canvas often forces a reevaluation and reveals much that the eye has grown blind to. Inverting colours, switching to greyscale, obscuring, etc, can have a similar effect.
When writing, speaking written words aloud often helps in identifying flaws.
Similarly, explaining why you’ve done something – à la rubber duck debugging – can weed out things that don’t make sense.