Briefing/asking a few 'wot ifs' is of course a very good idea.
However might I suggest these are better done during the good circuits immediately prior to getting out. Once it is clear you are getting out I don't want the stude to think of anything other than stamping out another circuit like the last.
As ever so much depends on the stude, the standard of ATC and what access you have to go and join the tower man while your lad or lass is doing their stuff.