In my experience, the current Flybuys system is working well. I use a BNZ credit card to get points ($15=1point) and shop at New World, and fill out surveys for Colmar Brunton. I do most of my spending on my credit card (including groceries) and clear it each fortnight when I get paid. On average, I accumulate about 250-300 points a month, sometimes more if I can put a big purchase on the CC and clear it straightaway.
I have my Flybuys reward set to Fuel Discounts at Z and Caltex. Each Flybuy is worth 0.75c discount (4 points = 3c discount). So for 300 points I get a $2.25c discount on fuel. If I manage things carefully, I only buy 50L of fuel each time, so the cost of that fuel ($112.50) is now free. That means that each one of those Flybuys points is worth 37.5c. Back when I used to just redeem them for rewards (e.g. appliances), the average value of a point was about 15-18c, so the fuel discounts works out best for me. It's even better than the CashBack rewards programme on ANZ credit cards. They give you 1% cashback, for instance, which is $200 back for $20,000 spent. The same $20k spent on a BNZ Platinum Visa generates 1333 points, which is a 1000c discount ($10/L of fuel). Now that you don't have to use your fuel discount in one go (e.g. if I had a $10/L discount, and petrol cost $2.25/L, I would have a $7.75/L discount left for next time), that 1000c discount works out to be $500 worth of fuel (when used for 50L at a time)., or 2.5x the value of the cashback.
Without making any significant changes to my shopping habits (shop at New World, use my CC and clear it each fortnight, fill out some surveys) my total fuel bill for the year is under $100. True, I'm only going through a tank of petrol every 25 days, but for my circumstances it works out well.
And then there are the sneaky little bonuses - like Disney+ offering 300 FlyBuys for signing up. I used a burner account to sign up for a new account, paid the first month's fee and collected the points. Net return = $100 of petrol.
Does it work for everyone? No. But for me, I'm pretty happy with the current Flybuys set up.