I tried a few some months back. Being in outer NE Melbourne I found them to be a waste of time as data varied among apps from being crowd input to company data. Some servos reliably change their prices at 2PM and others at random times in the arvo.
Since my vehicle uses 98 I have learnt to ignore anything Shell because they are adding 20cpl now while Caltex and BP at still at 17 or 18 cpl above 91. Premium is not always included in the apps. Every servo within a 10-20 minute radius (and often further) will have the same prices at the end of most days, although an exception happens now and then where one goes up 20cpl and the others do not follow, but back to business as usual by the next afternoon when they are all the same again.
We do not drive a lot so just watch the trends and don't let the tank get so low we would have to buy within a week.