That's embarrassing! I've been doing it wrong for years! I think it's because you cannot SEE the multi-port valve labels where it's under the deck.

Now here's the thing: From my experience, of virtually ALWAYS having gem-like sparkling clear water that is very stable as long as I follow my own rules of regular testing and minor adjusting, it seems it doesn't matter as much as you'd guess whether you use "Rinse" or "Waste". I ALWAYS backwash until my sight-glass runs clear for at least 30 seconds. The sight glass always runs clear for 30 seconds on backwash before it goes cloudy, and you certainly don't need a white card to see it. But there's no sun glare on the glass to confuse me.