You should ask yourself a question:
instructor or supervisor ?

If you are instructing then instruct,, on every aspect of the hobby..

If you do not have the time then do the person you are to be instructing
and yourself a favor,, make the time or pass on that days lesson..

Sadly it is all too common in todays world that many people do not wish
to help others,, yes,, even in this H O B B Y ....

For me the best answer would be,, if you are going to instruct then do it..
But do it totally,, for you,, for your student,, and for those that could be effected..

Flying is fun..
Instructing is <usually> fun..
Helping someone else to have fun is major fun..