HMS Hood's refit could not be frozen early

Why were parts of HMS Hood's planned 1942 refit still unfinished when she was sunk?

Because power, radar, fire-control, and secondary-gun choices were still being revised to incorporate the latest technology.

The projected Hood refit remained incomplete because designers were still incorporating rapidly advancing wartime technology. They needed to determine the ship's electrical demand and where the newest radar and fire-control equipment would fit. Secondary armament was also unsettled, including whether sufficient 4.5-inch weapons were available or whether 5.25-inch guns should be used instead. Leaving parts of the plan open reflected moving technical requirements rather than the absence of a serious modernization scheme.