I'm interested that people need to adjust the tensioning bolt on their Spas. My Brooks is 30,000km* old <insert "nearly broken in" joke here> and I've never had to touch that. I broke it in gently, just dubbin and my arse (there is all sorts of advice on the web about soaking it in oil or water or baking it), and have mostly covered the saddle if I've had to leave the bike out in the rain (no cover while riding it in the rain, but between me and the mudguard, it doesn't get very wet).
.... I've just checked the brooks site about tensioning, and it says it should be flat when viewed from the side. My saddle, unsurprisingly, has a gentle dip in the middle - if I place a book across the top of the saddle, there is about a 5mm gap in the middle. Brooks says this means it needs tensioning, but is there any reason to do that if I am comfortable as it is?
(I'm a slow rider, so 30,000km > 1,500 hours in the saddle)