For my own experience in another US boutique, I think I can safely generalize (to apply to SF) that whatever winning argument an SA uses to get a particular client a coveted bag offer varies greatly. In 2023, I was roughly 5X between bag offers and I ended up not accepting two offers. In 2024, I was maybe 1.5X and I got an MKII noir epsom. Perhaps tenure; type of spend; potential for future spend; and even low maintenance amiability may be factors too.
ETA: if a persons SA is overdue for the SM to allow her to offer a bag, that may be a factor unrelated to a client profile.