Series drift is usually blamed on the model. Look at the ledger instead. The character was described from memory at every job, and memory rounds the corners as it goes. “Chestnut hair in a low twist with a steel comb” in frame one becomes “dark elegant hair” by frame four, and the audience watches a stranger take her place. The repair is clerical: enter her once, on a ledger card you paste rather than retype.
Five fixed lines, always in order
Age — a number, and at this desk a mature one. Hair — colour, length and one habitual style. Build — two or three words, no more. Face — one or two details that survive any light. Signature — the one object or mark that identifies her at a glance.
Tick, do not trust
Hold each finished frame beside the card and tick the five lines one by one. Four ticks and one near-miss is a repair job for the editor. Three ticks is a regeneration — cheaper at the generator, at 6 credits, than at any later bench. The ledger is not bureaucracy; it is the cheapest quality control in the studio.