Botox muscle atrophy: loss of muscle volume (NOT function, specifically volume) due to prolonged Botox use?

Doctors highly recommend Botox because muscle atrophy is only temporary. BUT nobody seems to commend on loss of volume that is especially evident with lower jawline injections. There is vast clinical research supporting this as well as the whole book that touches on the subject: "Botulinum Toxins in Clinical Esthetic Practice". How much volume loss in the crow's feet area and forehead do doctors generally see after, say, 15 years of regular botox injections? Would frequency affect the atrophy?