Just because a take wasn't perfect from start to finish doesn't mean that there's nothing usable in there. Honestly, you may never get a truly flawless take. This is why we have editing. The editor uses the best parts of the takes and assembles them into a cohesive scene.
Also, never delete files from the card in the camera. That can lead to corrupted files and loss of your entire day's work. Shoot until the card is full, and have your DIT/media wrangler back up the ENTIRE card before it is wiped clean with a format cycle.