I have read the many post concerning the long miles required for Brooks saddle break-in with interest and a bit of confusion. Confusion, because typically it takes about 75 miles for me to have a saddle that well on the way to being broken in. This has been with a couple of B17's , a Champion Flyer and a B67. When I say well on the way to being broken in I am talking about them having fairly pronounced "dimple" as a result of the sit bones. Also note , that I weigh in here at 170 lbs. All this changed today.
I was riding a brand new Champion Flyer. Did about 35 miles and it looks like it was just taken out of the box. There appears to be NO dimpling whatsoever. There has always been some forming of the saddle to my backside. I think I know the reason. When I was first riding my other saddle it has been summer. I am talking about south Texas summer. In other words hot . Downing 2 water bottles in 15 miles or so would be the usual for me. Not today. One half bottle and one small 'ade when I was done. What I am getting at here is that I was not sweating much at all. Started out with temps in the 40's and then ended in the upper 60's. My theory is that because of the lack of sweat, the saddle remained had and did not have the opportunity to from at all to me. Often in the summer, the saddle leather is damp after a ride.
So, if you live in cooler climes and do not ride in the rain, this may account for the high miles you have to put in to break in your Brooks. The leather with this saddle does not appear to be any thicker . YMMV