The problem of the power reserve of a watch, whether quartz or mechanical, has always been fundamental, especially in tool watches, so much so that the ISO6425 specifications specifically require that diver's quartz watches include a power reserve indicator. In fact, quartz watch movement manufacturers have inserted it in all mechanisms.
As we have already mentioned, the typical behavior of a quartz watch is that its second hand advance in one pulse every second. But in some cases, you see the hand "pulsing" every two or even three seconds. In this case, it means that the battery is low, and needs to be changed as soon as possible.
There is a potentiometer inside quartz movements that constantly measures the battery's remaining power. If it drops below a certain level, it sends the watch into a power-saving mode. When this occurs, and you see the second hand jerk forward every two or three seconds, it's time to change the battery.