Yes, I would recommend Inv and Vulscans only once per day (you can set it to repeat after 1 day), I then also use the 1 hour random delay.
I would NOT recommend at logon, this will only slow down the system when a user is trying to use it.
These settings work great 98% of the time, the other 2% cause issues when I have a user that turns on a laptop, checks email and shuts down... those systems are tough, but I get them eventually!
I am not sure if the one a day holds to the 24 hour clock or not, though if a system is off at that time, it will shift the time... If you need, you can set a time range, though I do not usually recommend it.