Currently, GNSS (Global Navigation Satellite System) positioning systems are becoming widely used not only in geodesy, but in broad positioning in very many areas of the economy and society. The growing popularity of GNSS, especially recent, is related to their significantly increasing availability and a reduction of measurement time to a minimum, while maintaining high positioning accuracy. High positioning accuracy is ensured, among other things, by applications that allow planning observation sessions so that measurement is taken at the best time windows. It is the moment when the impact of measurement errors due to the constellation of observed satellites is the smallest. The following paper presents an example of the use of such an application and its benefits for planning GNSS observations. This type of research is particularly important for urban areas, where conditions for receiving GNSS signals are particularly difficult. Increasing the number of observable satellites and simultaneously minimizing the value of the Position Dilution of Precision (PDOP) parameter allows obtaining position coordinates (3D) with high accuracy from the point of view of relevance to GNSS measurements. The paper demonstrates the fundamental significance of satellite constellation geometry for GNSS applications requiring high accuracy position determinations, for which correct planning of a measurement campaign is crucial. It avoids this way large errors or conditions that render the observations of a particular GNSS measurement method impossible.