We (Ford) introduced this procedure back in the 80's primarily to cater for engines that suffered early and premature failure of valve stem seals, before a material/spec mod was introduced. The removal of a Cylinder head is not always necessity (or recommended) In this case, the customer possibly does not need the expense of gasket, timing belts renewal, and other associated work.
This is acceptable service practice for CVH and Cosworth 16v cylinder head assy's.
It may take you 30 minutes to remove a head assy but there is a lot of work involved to carry out if to be done properly. I seem to remember that the workshop time was about 1 hour to replace the seals.
In fact, the simple answer was yes .. to his question. You're selling him a sledge-hammer to crack a nut.

HTH AJK.