However, even if I determine you're worth it, I will counter with a trial period and say (in writing) that you will get your top offer when and if you prove your worth to me and to the company. I am curious to know how would you react to that type of counter, if you don't mind sharing.
The original comment, though, lead me to believe that the poster does this as a rule, asking for 120% of the top and expecting to get 90%. And while it is often the case that these hiring managers do play the game, I am merely drawing the attention that there are people out there like me (albeit probably not very common) who are not going to look favourably at ridiculous salary requests.
I can't help my gut reaction. I do, however, make room to change my mind and if there is meat behind your request, I will readjust my thinking. If I catch you in a bluff, however, because you think it's what you're supposed to do...outcome - not so good. :-)
Remember that the negotiation is the 5-minute tip of the iceberg. I try to build the negotiation by knocking your socks off at every point of contact, using whatever resources I can muster. (Want to see code? Then I'll apply all the professional spit 'n polish. Want me to present something to your team? Then I'll consider all angles, including business angles and software engineering analysis, trying to make it as intellectually interesting as possible.)
If you give me the chance and a premium, I'll continue that game to your trial period. (Though I'd maybe try to slip in a higher number, because I'm assuming more risk. ;)
But yeah, if you accept my first offer immediately, then I'll feel I've failed at negotiating. (I believe there's something absurd and horrible about the whole situation, but that's the madness of a market economy, with its built-in antagonism between buyer and seller. Graeber's _Debt: the First 5000 Years_ explains why so many people are repelled by salary negotiations.)
However, if you prove with all the stops that you are worthy of the premium, I will know what you are capable of when push came to shove and that is what makes you worth it.
This can conflict with most management styles, those which favor uniformity. Hence my choice of companies I work with.
I say this from experience. I asked 100K for a job and the company came back to me turning it down and stating they only have 60-70K allocated for it. I countered with 90, told them how I am different from the other candidates, and got a favorable offer ... too bad it was a few hours after I had just accepted another offer.