If you are talking about not being able to turn in assignments then there are assignments almost every chapter in year 7 and always 1 per chapter in year 8/beyond hogwarts.
As for countering it, you can minimize/eliminate the risk of anything breaking before turning it in. The problem occurs if your game disconnects during the final conversation, as when you load the autosave the conversation is no longer available and you have no way of progressing the assignment.
To "prevent" this, you have to create a manual save before talking to the person. As an extra precaution you can enable flight mode while you turn it in and turn flight mode off after the conversation has ended. What these steps do is prevent the game from autosaving if you disconnect, as the game autosaves every 2ish minutes and when you quit the game. In the event of a problem, your most recent save will be the manual save before talking to the person.
