How often do you (and should you) change a cartridge filter?

Recent first time homeowner with a pool and our pool service suggested we don’t clean the filter until the gauge reaches 10 psi. We seem to get 3 months out of a cartridge filter (75 sq ft), whereas I’ve seen comments from other people getting 6 months to a year out of theirs. I also utilize a skimmer sock to keep out the larger debris. It just seems like once I clean the filter it goes downhill fast in terms of effectiveness.