I noticed that students tend to hold back their striking power when they practise together. Completely understandable - but not the best way to go. This is the downside of semi-contact kind of training: stopping your punch.
Well, actually you shouldn't do that but it is quite difficult. Do a real punch, but not penetrate the body of the opponent. This is different from stopping your arm from moving. It is difficult to explain. Difficult to demonstrate. So I taught my students this method. So that they can develop REAL striking without actually damaging each other in techniques such as Kumite Gata 10.