I only own one automatic -- a Hamilton. If I remember correctly, the instruction booklet suggested the watch would run for up to 36 hours after being set down. I wear the watch most every day, however, on days that I do not put it on in the morning, at best I get 15-17 hours of running time before it stops. Does that seem typical? Do automatics, in general, not meet the advertised power reserve threshhold? Kind of like MPG estimates!