Default RAM manager - clear memory??

Once in a while if I notice a slight lag, I bring up the task manager (bottom left when accessing recent apps), go to the "RAM" tab and tap clear memory. What's really confusing me is that it always closes a very high number of apps, even if it's only been a day since I've last cleared it. i.e. I just cleared it and it said "27 apps closed"! There have been times where it was even more...once it was almost 40.

I use the phone a lot, but it's always the same handful of apps... at most, even in a given week I don't exceed using about 6-10 different apps.

So can someone please explain to me what the hell are all these dozens of "apps" being closed? ??? I assume they're including system apps in with the regular apps, but what apps could they be? That's around 20 apps I had no idea were even running...