This is Lon's saddle break in procedure. I only use it on very thick leather like Berthoud. Most of Brooks leather is variable, some thin nowadays and I would not risk it. I've done it three times, twice with a Berthoud and once with a Brooks. I put a small amount of lanolin right under the sit bone, about the size of a quarter. I can do a very long ride quite soon. Mink oil might be better, I just have had lanolin and used it.

Lon's PACTOUR Blog: Breaking In a Leather Saddle