GLONASS has this neat live coverage map of earth:
The scale is the fraction of the current day when the 3D dilution of precision or PDOP is ≤ 6. Per this comment if the best precision were 7 meters, this is the fraction of the day at each point where the 3D precision would be better than 6 x 7 meters or 42 meters. That the map is almost completely clear means this is almost always met. Per this answer once can see a substantial improvement over performance in 2010 (from here) as the constellation is populated with more satellites over time. With insufficient satellite number, low precision (high dilution of precision) is often caused by the limited number of satellites in view at the moment all being in one part of the sky.
Question: Are there any similar maps for GALILEO?
Screen shot from here.