Opsman,
I got the info from our ops manual which is supposed to be JAR compliant. It seems to be a UK thing, the 1 in 28 has gone from our ops manual.
Any way, it's neither here nor there. Someone who hasn't flown a type in 3 months or 12 months isn't going to be up to speed. If they haven't got much flying experience or much time on type, then they will be working very hard to get back up there.
While it does cost money to keep an IR in reasonable shape, to keep a type rating "fresh" would be much harder.
That's the point I am trying to make.