What accounts for full scans running such radically different times?

Depending on which full scan I choose, the time to completion varies considerably. Normally, my scheduled custom full scan ("entire computer) takes 5 to 6 hours (1720273 files total). After less than 50 minutes, it covers about 47%. OTOH, a full scan run yesterday from the home screen took over 11 hours, and after nearly 6 hours it had only completed about 1.45% (1814199 files total). The custom scan screen has “enable scanning optimizations” and “decompress and scan compress files” checked. Do they account for the tremendous difference? Seems a little much. Win 10x64, 2 SSD, 4 HDD, CIS

Update: 10-2 scheduled scan took 7h 19min (1856922 files)

You only need full scans if you dont have a running antivirus,
or if you dont think its safe.

On the contrary, I’ve found that while most scheduled weekly full scans return a zero, occasionally they pick up one or more items that the constantly running a-v didn’t.

Hi genegold,
I am not sure what accounts for the huge difference in time of your full system scans, it could be numerous factors involved including the number of files recently changed or a recent Database update since the last full scan or even if the system is performing other tasks at the time.

The real-time scanner will only pick up malicious/suspicious items when/if they become active.
Non active malware isn’t causing harm, so clockworks comment does have merit.

I personally rarely run full scans.

Kind regards.

But if malware has become active, isn’t it too late?