Even though the use of protective glasses is important there are other factors involved.
Not mentioned, but the most important factor in safety when using steel targets is how they are mounted.
I once manufactured metallic sillouhette targets and did extensive testing.
#1 consideration for safety is that they MUST be allowed to swing or fall easily. If standing the bases must be only heavy and big enough to hold the target up. It must be able to fall when hit. This directs the splatter mostly (safely) upwards or sideways.
If swinging, chains should be fastened at the top of the target so it can swing backwards directing the splatter downwards.
Other targest, like dueling plates, must be able to swing easily sideways.
Targets improperly mounted account for most splatter that can come directly back to the shooter. I have a scar on my elbow that reminds of that truth and was part of my learning experience.
Steel that is too soft and can cavitate on bullet impact can, and will, also direct splatter back at the shooter. Hard steels or smaller calibers must be used on softer steel.