On UA, most FAs now go down the rows, taking primary (and if necessary, secondary) choices and sort in the galley (on UA875 in BC, they had little Post-it notes with seat numbers that they arranged under larger PINs with the choices). Some of the veterans still bounce around the cabin (force of habit, I am sure) and either do it by seat, or by seat pair (so they ask the status person first, then their seatmate, and sort the SM in the back).

On AA, when travelling on even-numbered flights, meal requests are taken front to back. On odd-numbered flights, it is back to front. Status (is supposed) to have no bearing.

On international flights, UA also boards the same basic three entrees in both First and Business, with a fourth entree for First. While unused F entrees are formally designated for the FAs, on many flights the F and C galleys will coordinate to try and ensure that any spare F entrees are dedicated to meeting C passenger meal requests, with the FAs taking what is left of the mix. Also, at times some C pax have been offered spares of the fourth F entree if their choice is out.

As a 1P on UA, I have been asked my secondary choice only once and have never not received my desired meal choice in scores of flights.