Not intended, but not an exploit.
So that falls under the category of "creative use of existing game mechanics?"
Don't get me wrong, I take advantage of it. i've even been pretty lucky with getting over 50% of my level 27 schems on the first try.
My opinion is that if the devs really didn't want us to do it, they'd find a way to fix it. If they can't be bothered enough to actually fix it, then there's no reason not to do it.
And how do u do this? getting 50% on first try?