From what I've heard and watched on a youtube tips video, this is wjere Apple shines: able to hold onto many apps open as long as it can; that this is making use of their powerful chipset inside. The tip said that opening and closing apps spends more power to launch the app itself rather than to let the app running in background.

I need a second opinion though.

Yeah i've seen so many people say this and it seems to be true.

But will keeping some apps that you only use once or twice a day on the background for the whole day, drain more battery than you opening and closing it just when you need it. See what I'm saying?

No. Apps in the background are almost always in a suspended state and don't use processing, and iOS limits them to very few processor cycles - basically to check for new mail notifications, etc.

There is little reason to close apps in the background except if the app is acting up somehow.

I leave all apps on in the background. Apple manages RAM awesomely. I never see any slowdowns or hiccups. They reload sometimes if it’s been a while or if they are RAM intensive.

The only apps I force close are games. And even then, I’m not entirely sure I’m supposed to do that.

You don't usually need to close apps, but sometimes there's a glitch where it keeps running in the background.

iOS permits apps to be run in the background for up to 10 minutes. No app can run in the background for more than 10 minutes (unless for something like playing music).

Leave them alone. iOS does it all for you. The more you close the more battery you will use long term.