With the A-4, just remember that the first 3 models (A4D-1, A4D-2, & A4D-2N... redesignated A-4A, A-4B, & A-4C) did NOT have the fast-responding Pratt & Whitney J52... they had the much more sluggish Wright J65 (license-built version of the Armstrong-Siddeley Sapphire 100), and so keeping the engine spooled up was far more important.
When the newer models came out, it was easier to keep the same procedure for all Skyhawk models, so as to avoid a situation where a pilot used to a later model forgets to ride the upper part of the power curve when flying an earlier model.