Couldn't really care less what web pages you throw, clearing out the multitask and power cycling the device every now and then is an important step for any computer out there. There is a reason why it's one of the first troubleshooting steps to almost any issue.
I did state that it makes sense to 'close' an app if it crashes. Thats the only reason Apple lets you 'close' apps in this manner.
I think clearing out all background apps, and power cycling WERE important things for computers. And on Windows os Mac OS they still are to some extent.
However, not with the iPad. My girlfriends mum has had an iPad for a year now and she doesn't even know how to get into the multi-tasking tray. When we go round and I get to use it, it still runs as smooth as butter, and her battery is fantastic.
It's an iPad, and there isn't really any wrong way to use it, and who am I to say I use it better than you. I am just sharing what I have found. And that is that closing background apps is not necassary in the slightest.
But if it makes you feel better and it keeps you happy, then keep doing it.