Multiple Daily Patch Scans - are they usefull

I have approximately 1300 PCs in remote locations (non-AD joined) that are turned on at different times of the day and some not very often. (one or twice a month)

I need to configure a Scan, Download and Deploy Configuration(s) that will scan each and every PCs soon after it is turned on and download and deploy patches. We do not set a reboot for these PCs and allow the user to keep the PC on until they are ready to shutdown.

I have considered setting one to start at 6:30 AM
Another at 9:00 AM
Another at 1:30 PM
Another at 4:30 PM.

I want to make sure that when a PC is turned on it falls into a patch deployment time frame. I have looked for the ability to scan for patches at startup but have not found that.

What am I missing. Is there another way.

We have a 10PM Scan for PCs that are left on overnight and it is configured to Scan, download and Deploy. The deployment window is set for 1 Am to 6 AM and force reboot is set because most of our clients are not using their PCs at that time.

Suggestions?

Thanks

Mike