Can be hit or miss actually.. anyone that says otherwise most likely does not deal with "very large" wire amounts on a regular basis.
In our experience, if you're under $10k for a wire you generally get it more or less instantly depending on the banks involved policies (some might credit next day, etc.).
However, once you start getting larger - wires "magically" will get "held up" for days/weeks on end. Generally, this is attributed (though not directly.. after much cajoling of a bank manager you might get a nudge nudge wink wink type of answer) to various Three Letter Acronym US law enforcement agencies. You will magically then get this money into your account at some later date, without any explanation or interest payments for the delay.
As I type this I'm trying to track down a somewhat large international wire which was sent weeks ago. sigh.
This is of course our experience, your mileage may and likely will vary
-Phil