I have flown the NG since it came, and I have deiced more times than I care to remember.
Show me where Boeing says this is a procedure after deice. I have never seen this written anywhere and it has never been in our SOP. And I say Boeing procedure, not a procedure that is put in the FCOM at the operators request.
It goes a long way to explain why some operators use forever to get out of the deice area while there is a long line of aircraft waiting to get deiced.
The SP for cold weather operations USED to include this procedure (not associated with deice) along with turning the nosewheels full right/left.
It’s not there anymore.
Never had a flap/slat problem on the NG either.