Some? Probably most. A project I worked on produced a "here is what we have just started doing" paper in year 1, then a "we have some more results" paper in year 2, and two slightly different "here is what we ended up with" papers in year 3.

But what do you expect? The system rewards publication above everything. And these are intelligent people. Of course they are going to maximise the numbers. Because if they don't, they get fired and replaced by people who will.

After 10 years in industry (publishing patents, not papers) I contacted my PhD adviser and asked what chance he thought I had of getting an academic job. His answer was equivocal, "none".