I don't get it

>spends 700 chapters making use of shadow clones in various ways

>using them to do paper work/boring business is for some reason out of the question

They needed to force drama somehow

If he uses 700 shadow clones that make boring work, once they dissipate, he'll experience the boredom having done boring work 700 times, making him die from boredom in ways unimaginable that even the most disillusioned sarariman committing suicide would still look like a softie.

What if he just uses one.

But when he sends out 100,000 shadow clones to fight all doing rasengans and then when they all come back to him he's barely tired at all.

But back to the point. He just needs one clone doing the work.

The most stupid thing concerning the clones is that everything that they learned, the original will learn it as well, which this fact was only revealed after the timeskip. Naruto basically wasted years at training Rasengan and controlling the Demon fox transformation when he could have learnt something better.

But he does use them to do paperwork/business stuff, the problem comes with how long they can possibly stay. Then again, this is the naruto series we are talking about, so it doesn't really matter.

That depends on his chakra reserves.

Remember pain arc? He had clones staying for days charging up sage chakra

Don't they stay forever unless they're dispelled?
Even so, he could just summon another one that would arrive in minutes.
I assume it was simply a matter of honor and presentation. Nobody likes to talk to your representative, much less a walking xerox.

They do, unless he spawns more clones or start using more of his reserve.
So if he spawns 10 clones, and limit himself a little, they can stay around for as long as they like.