OK OK I thought you wood have known in the Aust sun you will need to re sand and recoat every 12 months, regardless of what impressive claims manufacturers make.
no matter how many coats you apply it has to be done, a sad aspect of wood greying in Australia hence whywe dont have beautiful wood finish home here.
Just out of interest where did you get the Jarrah from?
its  almost a rareity here,  even my Iron bark supply has been almost depleted
 
General trivia:-
Sikkens has been bought out by PPG another good product/company bites the dust

https://www.twincreeksloghomes.com/blogs/wood-finishes/how-sikkens-became-ppg-proluxe-and-what-this-means-to-you

Regards Rob