If you were inconsistent before (3 days per week), of course running the same pace and increasing consistency and mileage at the same pace will work.
At some point though, when you stop increasing mileage, stop adding new workouts, and have consistency, an increase in easy pace is the logical next training adaptation.
He wants to do that now by building a base before adding in new workouts. It’s a great idea.
So many people preach “run by feel” until someone feels great and feels like running faster, then it’s too fast. If he sets aside 20 weeks where he truly runs by feel, going slow when needed, doing progressions when he feels great, even hammering some days, and slowly increases his days per week and mileage, he’ll be a much better runner than he is right now.
It’s not complicated. Get out the door for those 20 weeks, bump the days per week up, bump the miles up, and truly run by feel.
Sup below 8:00 miles and maybe you’ll run 16:15 instead of 16:50. I went from 17:3x to 14:5x when I went to college and had to bust my ass on easy days just to keep up.