It is feasible for you to run a periodic scanning on Windows 10 Windows Defender if you are using other antivirus programs other than Windows Defender. With this limited Periodic Scanning on, you are capable of scanning the computer with Windows Defender periodically on Windows 10.
Why does Windows 10 take so long to scan?
A Full scan can take a long time, particularly if you haven't cleaned up your temporary internet files recently. Six hours is a long time, but not unknown. If you prefer, you can still use the old user interface for Defender, it's still there in Creators, just not with a link to open it.
Can Windows Defender scan more than it is scheduled to scan?
Windows Defender should not scan more often than it is scheduled to scan. Search for and open Schedule tasks. In the left pane, expand Task Scheduler Library > Microsoft > Windows, and then scroll down and select the Windows Defender folder. In the top center pane, double-click Windows Defender Scheduled Scan.
How often should I run a full scan on my computer?
Microsoft recommends that you schedule a daily Quick Scan to check the areas of your computer that malware is most likely to infect. A Quick Scan occurs automatically per the Defender maintenance schedule. Running a daily Full scan is not really a problem or necessary but it is time consuming and excessive.
How long does a quick scan last?
This is what the last quick scan says "Scan lasted 205 hours and 36 minutes, 2966417 files scanned." funny thing is I know I didn't run the scan for 8 days. No threats were found at least. Depends on the size of your hard drive, how full it is and the processing speed of your hardware. Could be your hard disc dying.