That doesn't save fuel. The biggest fuel savings is cruising at you most efficient altitude until you can do an idle descent at L/D. That's typically about minimum clean speed or up to 10 kts faster. 250 kts closer enough. Zero out the K factor (727 PDCS - Performance Data Computer System????) or a modern FMC cost index and it typically defaults to 250 kts but the real best fuel speed is even slower. But the time goes up a LOT so the total cost goes up. However if you're trying to 'go fast' the most efficient way to save fuel/time is...leave early, taxi quickly, be ready, get short cuts. Inflight high speed descent is best, followed by a bit faster climb speed, with a higher cruise speed being the least efficient fuel burn to save time.

If the F/E had descended the cabin faster manually the problem could be avoided. Takes a bit of head work ahead of the descent to realize the programmed setting won't hack it. Either way, manually increasing the rate of descent or falling behind will result in a higher cabin descent rate. Due to the lower pressure differential it's better off doing the higher cabin descent rate at altitude. That's how the modern pressurization systems handle it.