My opinion:
The way one shoots (or should shoot) JPEG and RAW are completely different.
Shooting JPEG is very similar to shooting slide film as far as exposing goes.
One also does not anticipate doing much editing to these files.
Shooting RAW, by definition assumes a file not ready for publication.
Ideally, shooting RAW means exposing completely differently to the way one shoots a JPEG.
The idea is to maximise the capabilities of the sensor.
Straight out of the camera these files usually look horrible but appropriately edited in Lightroom (or whatever) the magic of RAW becomes apparent.
So, onto shooting both RAW and JPEG.
Fundamentally, as explained above, an ideal exposure for RAW and an ideal exposure for JPEG almost never intersect.
Shooting a JPEG exposed optimally for a RAW file often results in a completely unusable file.
Shooting a RAW file optimally exposed for a JPEG just leaves tons of image quality on the table.
My advice: in any one situation shoot either RAW of JPEG, never both!
JPEG is ideal for situations where a rapid turnaround is the paramount issue.
If image quality is the key issue go for an optimally exposed RAW image.
More advice: If one is trying to learn how to shoot in RAW, then, well, shoot in RAW!
All the time!
Learn from mistakes and move on - get thoroughly familiar with the art and science of RAW exposure.
Shooting RAW + JPEG condemns one to forever being mired in the wrong mindset for learning RAW exposure.
This is a somewhat editorial post that broadens the original question but is nonetheless worthwhile.
Tony Jay