How many letters does the top answer for “one after the other” have?

The most common answer is consecutive (11 letters).

Crossword clue: one after the other

1 answer found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

consecutive 11 letters wn-def

one after the other

one banded with others. 50% similar → bander

one behind the other 50% similar → tandem