I sand my deck every two years. It’s a pure joy to bring it back to ‘new’. I use a cheap Harbor Freight orbital sander after the Ryobi decided to give up years ago. Have had zero issues. A 12x16 deck takes about 90 minutes. The very first time though, after deck had ‘aged’ for 4 years, it took a few hours more. Doing it every two years provides for a nice and beautiful surface, easy to oil to bring out the colors.