It depends on how much water is going through the filter per day.
For pools the thought is to run the filter for an amount of time equal to the volume of water in the pool/ filter rate - I have a 13000 gallon pool and I have a filter that has a rate of at least 30 gallons a minute so I run the pump at least 13000/30 = 433 minutes or over 7 hours a day. For spas it is different as there is a lot less water volume; I believe I read somewhere that you are looking for 8 or 10 times the water volume for filtering.
Some tubs have a smallish circulation pump while others have a large one and others have none and use their main pump as the filter pump. My tb has a fairly large circulation pump and Artesian claims that it filters like 300 times a day ... maybe just a marketing claim!
I agree with Tman in that you are fine and may be able to cut it down somewhat and if you see your water getting not so nice looking up the time. I've never changed my filters that often, maybe once a week when the tub was new ... then as I got more comfortable I made it longer.
