Hell for leather
Definition 1 of 1
Pro Tip 1/3Urgency Context
Used when time is critical and someone needs to act with great urgency or haste. 
She went hell for leather to finish the exam questions.
Pro Tip 2/3Intensity Emphasis
Emphasizes the intensity and determination someone shows, often out of desperation or necessity. 
The players charged hell for leather during the final minutes.
Pro Tip 3/3Not Literal
It's a metaphorical expression and doesn't involve actual leather; don't misunderstand it as a physical action. 
With the deadline approaching, he worked hell for leather.