Etiquette
Reply times cut both ways
A judge who quoted is holding a slot; replying within a day keeps it, and vanishing for a week then expecting the quote to stand is asking a lot.
A quote is not just a number, it is a judge setting aside capacity against the expectation that you will act on it soon. How quickly you reply after receiving one is a real courtesy question, not a formality, and it is worth treating as such.
What a quote costs to hold
Once a judge quotes a request, they have effectively reserved a piece of their working time against it. Popular judges quote against a queue, and every slot held for an undecided buyer is a slot not offered to the next person waiting. A reply within a day or so respects that the quote was never free to give in the first place; a longer silence starts to cost the judge something, even before you have decided whether to accept.
The other direction
This cuts both ways. A buyer who accepted quickly and expects the judge to answer just as fast at every later step is holding the judge to a standard the judge was never asked to agree to. Turnaround on a finished review depends on queue position, prep and a judge's actual life, and that is a different clock from the one that governs replying to a quote. Prompt yourself, patient about delivery: that is the fair version of this etiquette in both directions.
If you need more time
If a genuine delay is unavoidable, a one-line message saying so is enough - "still deciding, will confirm in a couple of days" costs nothing to send and tells the judge whether to keep holding the slot or move on. Silence is the only wrong option, because it leaves the judge unable to plan either way.
There is no equivalent clock on the automated side of this market: a scoring tool has no slot to hold and no queue behind it, which is one of the plainer trade-offs against a fixed, instant price if speed matters more to you than a person's specific response. If what you actually want is a number rather than a reply to manage, a standard measurement has no reply-time question attached to it at all, and Rate Cock compares the two routes directly if that choice is still open. Reading a quote as a held slot rather than a standing offer is most of what this etiquette comes down to, and it is worth carrying into replying to the quote itself, which covers the actual content of a good reply once timing is sorted.