Good point..!
The structure of an LeD actually does that to a certain extent. When you see a reflection spot, with a PAUSE, there can be different time taken by different learners. Some learners won't even bother to pause and reflect. they will just mentally answer it.. and will check it in the subsequent summary. While others get a chance to pause and think as much they wish to.. and compare their answers with the summary.
Also, Ask a Question feature available 'at the point' where you are unclear is useful to get more information about a concept.
Same happens with LbDs, where the 'constructive and customised' feedback helps not only the ones who selected the correct answer, but also to those who gave a wrong one! Those who feel the need for learning more to 'catch up' can use the LxTs/Discussion forums.
-sameer