It wasn't loading quickly enough on my system.
One thing Mourinho said was that kids should understand the objective of every session. I think this may have been imparted in KNVB. I'm guilty of not always doing this because I sometimes spend so long working on explicit technique, through identifying so many faults, unlikely to be corrected by many other coaches, players become restless to play SSGs.
Hence, I rush the instructions because it seems like their concentration has lapsed.