Why you have to pay for two trips
In the best of all possible worlds nobody would need executive protection (and we would have to look for real work). Unfortunately, this is not the best of all possible worlds. Because of this, people need protective services, and these services are expensive.
One part of this process is the advance. In essence, the trip is taken, in advance, by an individual or group of individuals. For those just getting involved with protective services, it can apparently seem puzzling that we have to send a team to visit an area with which we have some familiarity.
As it turns out, however, advance work is arguably the most important part of any detail. If the advance work is done properly the likelihood of anything bad happening is greatly reduced. And, if something bad does happen, the likelihood of it being dealt with appropriately is greatly increased.
What is done during the advance work? This can vary, but in general someone does a walkthrough of the trip going everywhere that you will be going to on the real trip, checking security at each point, looking for areas of possible difficulty, checking your lodgings, assuring that all anticipated services will be available, checking that all the arrangements that need to be made have actually been made.
Other things that may be done might include checking that appropriate medical facilities will be available, making alternative plans for exit in case of an emergency, and checking in with appropriate contacts. If the corporate plane will be used for transportation, airport security will be reviewed as well as alternative airports.
If the advance work is done properly, there is a high probability that the trip itself will be problem-free.