I am no expert on in-water recompression, but the little I know does not include any protocols that require as much as 3.5 hours. Richard Pyle's study of IWR breifly describes three protocols, and as I read them, none comes close to 3.5 hours.
I personally know three people whose DCS was resolved through IWR using the Australian protocol (I think). I was not present for any of them, but all three had their symptoms completely resolved in a fraction of that time.
The Australian table runs between 2.5 and 3.5 hours depending on 'severity'. US Navy is 3 hours plus depending on symptoms (Type I or II)