Depends on what kinda art I'm doing, and what kinda scars. How deep, how superficial...
comic, just a block lol; as long as it gets the point across, ya know? I got like 20 drawings to do a week I do not have time for nuance;

outside of the comics, I put more depth into the deeper ones, and actually bother with small superficial ones. This character has a good mix of both; you'll see little very light lines and the darker lines both all over his arms...

comic burn scars? boring red lump. ease of drawing. If it was more important I might put a smidge of effort into it, but here it really isn't. Heck, I forget it half the time. But alas, burn scar;

outside of the comic, again i put more texture and colours into it. Just a hodgepodge of reds and pinks all swirled together.

+ another draw that makes the scar stand out, and just kinda a fun mix of simplistic scars and complex burn scars, just to see what loses priority first when doing simpler drawings.

I also have characters with frost bite scars, lightning strike scars, so on and so forth because Oh boy do I like beating up my Ocs! But I don't inundate ya'll with the sheer amount of ways I find to hurt my poor little guys and gals.