I have, on occasion, literally "ripped the lips off" of a Crappie, when they tangled themselves in a brushpile. But, that was back when I used 8lb test line. Nowadays, when they burrow into the cover, it's almost a foregone conclusion that I'll break the line, before they submit to any coaxing or pressure .. simply because I'm now using 4lb test. However, that also depends on how deep into the "cover" they are, when they strike .. as well as "where" they're hooked.
If they're hooked in the roof of the mouth, which is where I hook them most of the time when using jigs, there's a better chance of being able to keep steady pressure on them & guide them out. Chances are that they've got their mouths closed, when hooked inside the mouth. When hooked IN the mouth (ie in the lips or lip membrane) they tend to keep their mouths open ... and your pulling pressure also forces their mouths open. This makes them "larger" (in the mouth/head area) and less subject to being pulled thru a narrow gap in the entanglement.
This is just my "theory", and in no way is it a scientific fact, that's based on research.
... cp