Where the name comes from
Abner E. "Abby" Singer worked as an assistant director and production manager from the 1950s through the 1980s. According to his Wikipedia entry, he would say, "Fellas, we'll do this and one more and then we're moving," giving departments a head start on breaking down. The name stuck to the second-to-last shot (Wikipedia).
Why ADs still call it
The Abby Singer is a scheduling tool. On a day with a company move after lunch, departments that won't be needed for the final setup can start wrapping and loading while the last two shots are done. If grip knows the dolly track won't be used on the martini, they can pull it during the Abby Singer and have the truck moving sooner.
Here's a fictional day with a move. Scene 14 at the diner has four setups (A through D). Setups C and D are a two-shot and a close-up from the same side, with no dolly.
| Setup | Description | Called as | What departments start |
|---|---|---|---|
| 14B | Dolly in on Rosie | ||
| 14C | Two-shot, static | Abby Singer | Grip pulls dolly track; art starts wrapping the kitchen |
| 14D | Maya close-up | "Last shot here" | Electric strikes lights not in frame; transpo stages trucks |
| MOVE | Company move to garage |
At end of day, the order is the same with the martini shot in place of "last shot here", followed by wrap.
How it's announced
The 1st AD says it on set and on the walkie: "Next shot is the Abby Singer, 14C, two-shot. Abby Singer, everybody." Some ADs just say "The Abby" or "Abby's up next." The 2nd AD then starts on cast release times and checks whether anyone needs to be at the next location early.
When people get it wrong
Calling it too early is the usual problem. If the AD calls the Abby Singer and the director then adds two more setups, departments that started breaking down have to bring gear back, which costs more time than calling it late would have. The AD should confirm the last two setups with the director and DP before announcing.
The other mistake is confusing it with the martini. The Abby Singer comes first, then the martini. On a split location, it's also easy to forget that "last shot here" before a move isn't a martini, because the day continues at the next set.