I guess maybe I just don't get it, but after you are used to clip-less, forgetting to clip out is kind of like forgetting to breathe.

I think that getting used to clip-less is helped greatly if the following procedure is followed when setting up new clip-less riders:

1. Unless you know they need something special position-wise, set cleats up with all adjustments in the middle of the range.
2. Have the rider straddle the bike and clip in and out a few times while not moving.
3. Verify the the initial cleat position is close enough that they feel OK to try it.
4. Have them ride a few hundred yards and come back.
5. Remind them to unclip as they are stopping.
6. Ask them how the cleat adjustment needs to be changed. Discuss as needed and repeat riding if they are unsure.
7. Make changes to one foot at a time.
8. Repeat steps 4 -7 as needed increasing the distance ridden in step 4 as they feel they need to. This may take 30 minutes or so before you are done. Repeat again later if needed.

None of the folks I have done this with have had problems either with adjustments or with forgetting to clip out.