Well, there’s nothing wrong with his methodology, however from my experience if using an RTN 10 minutes is well worth the extra time. You should be logging raw data per point and this is satisfactory for PP to a local base also logging data onsite. Short observation times as you described are not sufficient for PP and in my opinion you are taking a big gamble with the accuracy of your observation with such a short time on station.
In our boundary surveys in high multipath areas using our state’s RTN, we observe 10 minutes per station along with a base also logging onsite. We use our Javad receivers for our boundary surveys and control surveys. They are very expensive receivers but well worth the money for our use. Usually our baselines are approximately 2-3 km. I always PP our data and compare the RTN positions. They are always within 2-3 cm, sometimes less than that. We use Javad, Emlid and Trimble equipment. I usually use an Emlid receiver as a base.
As discussed in another post, short baselines are your friend as well as time on station for sufficient data to PP. This will ensure that the point measured is as accurate as it can be. I despise re-observing a project… I lose valuable time and money.