Yes that is exactly what will happen.
Keep in mind it is NEVER recommend to setup all of your clients to scan at the exact same time. This can lead to timeouts and they may never return data to CM12.
That's what I thought would happen (re: the scan and the time-out). How to get management to listen? Can you help me there? (kidding)
There are a few ways.
1) Watch the load on your SUP and MP go through the roof, Sunday @ 10pm. Tell them that any computer NOT on at Sunday at 10pm will scan first thing Monday & Tuesday morning.
2) Tell them that a senior consultant & SCCM MVP, does not recommend this setting. I'm sure that you will find TONS of consultants here that will not recommend this setting too.
3) Ask for a SCCM RAP from Microsoft and watch their eye light up with you get a fail for this client setting.
Ultimately if they want to kick themselves, I'm not going to stop them, I will warn them it is a bad idea but...
Another important note here is that first, the software update deployment process does not depend upon the schedule update scan cycle nor the update re-evaluation schedule.
The update scan cycle is mainly to report status for undeployed updates while the re-evaluation cycle is to re-enforce deployed updates that are not installed.
Thus, having it run every 4 days is pretty useless (and arbitrary) unless Microsoft actually releases updates every four days which they don't.