The powers that be have decreed that the citizenry cannot cope with two different elections in the same year, far less on the same day.
The Scotland Act laid down that elections to the Scottish Parliament should be held every four years.
Subsequently it was decided that UK general elections should be held every five years.
The two fixed cycles clashed in 2015, and the Holyrood election was bumped forward to 2016. I trust that the election after that will be held in 2019, reverting to the original schedule.
Otherwise the Holyrood election will be skewed again ad infinitum.