Which of the following is NOT recommended when using a variable speed drill?

Leaving the bit in the drill when you're done using it is not recommended because it poses safety risks. When a drill is not in use, removing the bit helps prevent accidental engagement or operation, which can lead to injuries. Additionally, removing the bit can help maintain the sharpness and longevity of the bit itself, as it avoids potential damage from being stored in the drill.

Using sharp bits, ensuring the material is secured, and holding the drill at the correct angle are all best practices for safe and effective drilling. Sharp bits provide cleaner cuts and reduce the amount of force needed, securing the material prevents it from moving during drilling, and holding the drill at the correct angle helps in achieving the desired hole alignment and minimizing the chances of accidents. These practices enhance both safety and effectiveness while operating a variable speed drill.