Resting even does those wonders.It might be useful in an old one
Rested older hens for 4-5 days, pressure cooked meat was tender enough for a sammich when usually I cut it up in small pieces for stew/soup/salad...I was rather surprised and very pleased.
I learned most about longer resting times when butchering fresh turkeys.
First batch I did(rested 2-3 days) was like a wrestling match parting out, tendons were tight as hell.
Next year I let them rest for 5 days and they came apart like a baby CX and the meat was more tender.