I still repair jeans.
We also grew up in a time when anything NEW (and looked new) was cherished.
If I'm repairing an area from below the front pocket to below the knee, I will use the backs of the legs of a discarded pair of jeans and cut a great big rectangle large enough to cover the area.
I've found that if I use the multi-step zig-zag stitch that I don't need to turn the raw edges in. I put the patch on the outside of the jeans. I will tack down the loose edges of a worn out knee. Hate to get the foot caught in that spot.
I do have an open arm machine, so that makes it a little easier. Sometimes I can do two sides of the patch from one end of the jeans. Then I take them off the sewing table and turn them around and do the other two sides. Access issue.
Clear as mud?