We all have our own strategies for selling and our own feelings.
None are right, none are wrong.
These are my personal feelings
From a selling point of view.
I rarely accept the first offer (unless I am very happy with it). But I don't reject it either.
If offer by email or electronic means I will sit on it, without responding.
If it is by phone, I will say 'let me think about it, I will get back to you'.
Once I accept an offer, it stands.
Worst case scenario, somebody contacts me soon after and offers me ore money, but as I have already accepted an offer I am stuck.
Not accepting the first offer and waiting 24 hours would help avoid this problem, and maybe get you a better offer.
From a buyers point of view
It is frustrating to see anything on a sales board, that has been up for less than a day, that has sold before I even have a chance to login.
Especially if it is advertised, for say, $500. I would have been willing to go to $400 or $450, maybe even the asking price. And then find out later it sold for much less than $400.
But always Caveat Emptor - the buyer beware.
If I get sold a lemon, it is nobody's fault but mine. I also remember that my lemon may well have been somebody else's pride and joy.