They sent out a technical challenge to complete which took many hours (5+) and then decide not to bother responding with any feedback. This is very disrespectful of people's time. The minimum they should be doing is letting you know you aren't successful but really for this amount of commitment they are asking for they should be giving full detailed feedback. They are not a large bluechip company so thinking they can just get juniors to spend hours on challenges just to ignore them is very arrogant. I wouldn't advise people to waste their time unless their HR department decided to put a better recruitment process in place where feedback is given.