culture-wise, this is massively overgeneralizing, but it's based on both my experiences negotiating many 6-8 figure contracts, as well as advice from my mentors...

asian cultures (especially the japanese) don't believe in negotiating. an ask should only be made if it's reasonably expected to be accepted.

in contrast, eastern european cultures follow what i like to call moonshot. they will literally ask for the moon, even if they know it's shockingly unrealistic for it to be accepted.

euros, and particularly americans, frequently negotiate like it's a sportfuck, intentionally putting up roadblocks and trying to win points for the sake of bragging rights. also, some of these hardball companies will negotiate rates, and then after the key terms are done, try to throw in a bunch of terms after the fact (some that are ridiculous), via some low level employee. since the low level employee doesn't actually have authority to negotiate, they push really hard to make the deal go through and act like the terms are normal. in general, i've found it's better to just contact some department VP or legal directly, because asking for someone who actually has authority to fix stupid is really offensive.

as an aside, in asian culture, if conditions change over the course of an agreement and it gets tough or expensive for them, expect them to violate the contract and not care even in the slightest. the most common version of this situation is when the price of something changes greatly, they're simply not going to honor the contract unless it's in their favor, especially because actually enforcing the contract in a court is not really going to happen.

again, these are massive over-generalizations. not everyone in a particular culture follows these conventions. if you get onto an industry mailing list, people frequently talk about who is on which shitlist.