To be honest I'm not sure how much difference the "block" makes.
The definition of flight time, IIRC, is brake off to brake on (or chocks). The CARs never made any allowance for factoring other than for time claimed to obtain an ATPL as mentioned above.
The UK CAA were approached by a UK company about it but European law prevented it. They weren't happy about it in any case.
The local story was allegedly that Etihad applied for factoring but were turned down, EK having grandfather rights but supposedly time (un)limited!