Most of our alerts can be run at any time you choose. You can request a specific time (look for this to be automated on our website soon) and/or a specific interval, so that you receive our alerts when they'll do you the most good. Some of our alerts, however, have to be run at a certain time of day or at certain intervals because of the way they're built. ID46, for example, needs to run in the evenings because the logic it's built around assumes that. If you run it in weekly mode, it needs to run on Satuday evenings because the logic just isn't flexible enough and the alert might not fire properly for you. We've tried to design all of our alerts to be of the 'run-anytime' variety, but it just isn't always a feasible option. If you need the report in the morning, it will run the night before and be waiting for you on your desktop.
Going forward we are converting some alerts we've had problems with to run on this sort of mandatory schedule, and some new alerts will require it as well.