Flawed thinking?

[Coveyleader]

You hear alot about carrying expandable broadheads for long follow up shots (saw it today on my favorite youtube channel) on elk. The more I think about this, its pretty flawed thinking. Lets say you shoot an elk, it runs out to 40-50-60 yds and is looking back, or is walking slowly away but at a hard angle. At severe angles, do you think you can maximize your penetration using an expandable head? You will most likely being shooting at a hard quartering animal at best. If I know it's a bad shot, I will try to get an arrow into the elk at any angle possible and hopefully drive the arrow deep which seems counterproductive with a mechanical.

I'm batting 1 for 4 on follow up shots where the elk actually gave me a good broadside shot after an initial bad hit. All the rest were quartering to me, or hard away. One I jumped 3-4 times, and never had a good follow up shot angle and he was always 80-100 yds ahead of me. When I finally caught him in his last bed, it ended up being a close shot, but very hard angled. I don't see the logic in this though process.

Thoughts?