Mission be a tough one to do if it was worked out better...Numbers are just random...it would have to be something that gives Hackers no less then a couple mins to waste or they wouldn't be able to do it and lose it...
Time has always been short with all hacking. It could be very interesting if you would start a very short timer.
For example, once you crack the server and login as admin, you get a 5 minutes timer until the server shuts down due to unauthorized access. During that time, you try and do the mission objective with the timer always above
Failing the mission can cause a reputation loss.