A back is the largest single canvas on a body and the only one where a realistic image can be given the room it needs. It is also the one people rush, and rushing shows.
Federico works a back as one image, not a collage: one subject, placed so the spine and the shoulder blades carry the composition instead of fighting it.
Two of his finished backs took seven and eight sessions each, spread over months. Anyone quoting you two sessions is describing a smaller tattoo.
It does not have to be, but it works better. A back built as separate pieces added over years rarely reads as one image from across a room, which is the only distance a back is ever seen from.
The spine, the lower back and over the shoulder blades are the sharp parts. The broad muscle either side is among the easier places on the body.
Yes, and that is often the sensible way in: the first session sets the layout and the main figure, then it continues on the next stop.
Requests go straight to Federico, not to an agency inbox. He answers from his own address.