I've previously posted sharpening a twist drill by hand.
https://youtu.be/wStrlkuwMYc
I do this routinely because it is quick and easy. Here's a video of using a hand sharpened 1/2" twist drill to drill through some 3/8" steel plate.
The drill isn't sharpened precisely, so each of the two curls are different size however it works and is efficient. It takes about two to three minutes to sharpen a drill depending on how dull it is. A broken drill will take several minutes and may need to be heat treated.
