How long can my voice or video answer be?
Long enough for the tier you are answering. The length is something your own tier describes, for example a voice note up to three minutes at one price and up to eight at a higher one.
Match the length to the price
Askers compare what they paid against what arrived. A long answer to a cheap question trains people to underpay; a short answer to an expensive one is where disputes come from.
60 answers in the Nudge help centre.