Admittedly, my memory is not as good as it used to be but I honestly cannot remember the last time I initiated a manual scan on either of my two primary systems. And it has been a very long time for the other 3 systems here, 2 of which are regularly (well, regularly before this covid-19 mess started) used by invincible ("it will never happen to me") teenage grandkids and house guests. I mention the grandkids and guests because I know they are not (nor do I expect them to be) as disciplined, experienced, or "security aware" when it comes to "practicing safe computing" as I am.
So what do I do with my computers?
1. They all run the latest version of their respective operating systems. For Windows, that's Windows 10.
2. I keep the operating systems current. That is, I have not dinked with Windows Update's default settings.
3. They all run Windows Defender and it is kept current.
4. I avoid being "click happy" on unsolicited popups, links, attachments and downloads.
IF I suspect something suspicious on one of the "guest" computers, I might manually scan it with Malwarebytes just to be sure Windows Defender (or the user -
always the weakest link in security) didn't let something through. But ever since I started using Windows Defender (actually starting with its sibling, Microsoft Security Essentials), Malwarebytes has never found anything beyond a couple "wanted" Potentially Unwanted Programs (PUPs).
Bottom line, if you follow steps 1 - 3 above (most of which is automatic if you don't dink with default settings), number 4 (don't be "click-happy") will become your top priority and primary defense against the bad guys.