They do, but for small scale projects like satellites we tend to push con-coat until we have a good confidence the unit is working. Removing conformal coating t

They do, but for small scale projects like satellites we tend to push con-coat until we have a good confidence the unit is working. Removing conformal coating to replace a failed component or change a resistor can be quite tricky, especially for epoxy based coatings. So there is a long time without any coating (up to spacecraft assembly).