I often use 121.5 for Practice Pans. Normally they are dealt with excellently. Occasionally, we are asked to do a Practice Pan for ATC student training. The last one I did, just before lock down (a very short of fuel , above cloud & unsure of position), was not so well handled and I'm sure the student got a good debrief. The fact that things went poorly was a valuable lesson for him I'm sure.