I don't subscribe to filter replacement by hours, it's not logical. Obviously a 1000 hp running for 500 hours uses way more fuel than a 30 HP engine running for 500 hrs. If you have to change your Racor filter element after running less than 1000 gallons of fuel through it, then it's very likely your tank is contaminated.
This question of fuel (or oil for that matter) filter elements deteriorating or disintegrating, or somehow going bad, has been around for decades. Because of that, 17 years ago I placed a Racor 500 element into a mason's jar of diesel fuel. It's been there, sitting un my shop, ever since, with no visible signs of deterioration. I'm not recommending this, I'm simply saying that it's probably not an issue. Caveat, that it is a genuine OEM Racor element.
I've personally replaced hundreds of filter elements in my career, many of which have been badly neglected and not replaced in years, and never have I encountered an element that had lost its structural integrity.
My recommendation, change fuel filters, primary and secondary, when absolute (not relative to the starting point) primary vacuum reaches 5-7 in. of hg., with the above mentioned 1000 gal threshold taken into account. Engines with diaphragm lift pumps have the lowest vacuum threshold, while engines with gear lift pumps are able to endure far higher vacuum, however, I'm not endorsing this. Chronic high vacuum can lead to injection pump cavitation, and damage.
You can test vacuum gauge operation by slowly closing the selector or supply valve, while the engine is idling in neutral, while monitoring the gauge, it should rise slowly.
Filter elements are pretty cheap, so if you don't meet one of the above thresholds, I'd replace them after no more than 2 years.
Note, I have encountered a couple of cases where electric lift pumps installed
before primary fuel filters, which are used continuously, causing inaccurate, low vacuum gauge readings, and erratic engine operation, or even sudden shut down.
Finally, both Racor/Parker and every engine manufacturer I've encountered, call for the use of 10 or 30 micron elements in primary filters. 2 micron elements are strictly for secondary filtration.
More here...
Filter Service: How Often Should Fuel and Air Filters be Changed? | Steve D'Antonio Marine Consulting
Primary Fuel Filters 2, 10, 30 Microns? | Steve D'Antonio Marine Consulting