Acceptance flights

[Curious Pax]

From time to time I see mention of 'acceptance' flights for either new aircraft fresh from the factory, for used aircraft going to a new operator, and occasionally for aircraft returning to the lessor. Out of curiosity, what is being checked prior to acceptance - just the basic up/down/left/right/ability to fly (which presumably is ticked off fairly early in the proceedings), or do things get quite complex, and take a flight of several hours (which is expensive I imagine)?

Thanks for any answers.

[Knold]

It's up to the buyer / lessor how much they want to check. If a flight is done the standard is that the seller / leaser treats you to it...