Why would a host choose a gallery or a reception over other styles of service?
A host might choose a gallery or a reception over other styles of service, because the open concept of the gallery allows guests to mingle and freely move about the room. Many hosts prefer this style of service, because it can still feel elegant, but not as oppressively formal as a sit down dinner in which guests can only talk with the few people seated next to them. In a gallery or reception, the guests can enjoy greater mobility, mingling, and discussions, which can feel more comfortable and put people at ease by allowing them to move around to talk to whom they please. If the host is throwing a party for a potential client, then it would be very advantageous for them to make the client feel as welcome and comfortable as possible.