Hull condition and replacement timing shaped battleship modernizations

Why were some Royal Navy battleships modernized much more extensively than their sisters?

The Admiralty weighed hull condition, available time and money, and whether new Lion-class ships would replace the vessel before the reconstruction paid off.

Money, time, physical condition, and planned replacement explain the unequal reconstruction of Queen Elizabeth-class ships. Barham and Malaya missed the most extensive work because funds were scarce when time was available, then time was scarce once more money appeared. The Admiralty examined each hull before committing to machinery and superstructure changes, since an old structure might not carry the added weight or last long enough to repay the investment. Even within one class, some ships therefore received much deeper work than others. The expected arrival of Lion-class battleships further reduced the value of rebuilding a vessel that would soon leave front-line service.