Individual observations are less expensive. Although allocation of expenses to particular projects is subject to criticism, the cost per observation does seem considerably less with robotic telescopes. He finds the manual observing was about twenty times as expensive per differential photometric observation of a variable star. These dramatic savings were realized in time not spent at the telescope as well as in the large amounts of time spent reducing data that had to be manually corrected for the inadequate data logging system used at Kitt Peak. More data can be gathered per star.
Automatic telescopes can observe during all clear weather available.
Manual observers rarely do, even if they have the stamina to try. Thus with robotic telescopes analyses are less likely to be based on an inadequate number of data. This is too valuable a quantity to waste on such repetitive tasks as manual observing. The same qualities of automation that make it efficient also make it effective. All data are gathered in the same way.