Well tbf, even if you don't review the 50/50 stuff, the way it works means that you may choose not to review a decision, because you haven't got enough reviews left, and even if technology would've overturned it, you have vague doubts that it would, particularly early in the innings. And that just sucks.
An example in a different sport which uses referrals was last night in the tennis, where Wawrinka didn't want to overturn a decision as he was weary about how much of a howler it was, yet his original conviction was correct - it was in. And that has 3 referrals a set - much more than 1-2 referrals a game. It could well have cost him the match.
Having only 1 review means that some things that would've been overturned may go unreferred, even if some **** didn't waste it on themselves, and that is ineffective use of UDRS, I feel.