Once you KNOW that you have quality bearings, and once you KNOW that they have quality grease, and once you KNOW that they are adjusted correctly and once you KNOW that you don't have the faulty designed spindles, then it might make sense to extend service intervals. But we know that many never reach that level and have failures.
My old van has similar bearings and I have only serviced them a few times in 40 years, but they are quality parts, not the junk found in the trailer industry. Of course it has disk brakes and there is no need to disassemble like drum brakes, thus the reference to brake types.