Feline, your link is to a commercial organization and they wrote the following:
"Once a wall is wet, it can take a long time to dry out. There is plenty of research out there which tells us how long it will take - the process depends on how warm the air around the wall is, how dry that air is and so on - but as a rule, if your wall is a metre thick (common in old stone built houses) it can take a year for each inch to dry out properly - so working from both sides - you'll dry two inches of wall a year."
So this is where you got your 1" a year from. What they claiming is a 1 metre wall would take 19 years to dry out - they are living in cloud cuckoo quack land. Also they don't provide references to the research they claim to have seen. It would depend on the type of stone used, but their rule of thumb does not take this into account.
I have had a brief look at other parts of their prose and will read more next week when I have time, but from what I have so far read, they are a quack outfit selling their services to the gullable with typical quack talk such as: "'allowing the walls to breath" and using copious ! !! !!!!! !! ! throughout the text.
I know a 92 year old gentleman who lives in a detatched house which I cannot stand to be in for more than a few minutes due to the smell/sense of damp downstairs. Summer or Winter, when I walk upstairs it is completely clear, but walk down the stairs and it hits you, but he is unaware of the damp and his wallpaper looks fine.
I have stopped rising damp in my home where it occurred in a small area, it is very easy - install a DPC that is 100% impermeable to the passage of water. In my house's case, an area of wall was damp and the skirting there had rotted with dry rot, but there was not the horrible damp house smell/sense. The cause was a DPC which was not 100% waterproof as it was made of layers of slate with morta inbetween AND ground wetter in that area compared to other outside walls of the house.