The time of data collection varies greatly, depending on the monument location. Other monuments are on street corners or in public parks. When using GPS data for crustal deformation studies, sub-centimeter precision is a requirement. Even the slightest errors can destroy your precision, and waste time and money. A typical GPS antenna set-up over a survey monument.
Many factors contribute to the precision of the antenna set-up.
These include soil type, heat, humidity, wind, livestock, and just plain human error.