Knowing when to scrap a project and start over versus spending the extra time in trying to fix a mistake is a constant struggle for me. Especially in cases where there is quite a lot of effort put into the project leading up to the dreaded mistake or design flaw.
For example, the image below shows a couple of practice cards where I was playing with the layout and how I wanted the card designed. If you are familiar with the masking technique, you already know that it can be a bit tedious and planning is super important. You have to know which images to mask off and when before you stamp and so I took a few minutes to practice on a few cards before I settled on my final design which is the colored panel in the below image.