For the better part of my career most of my work has been project based. Either several smaller projects at once, or a single ginormous project.  If you have ever been involved in a large project you will know that inevitably something goes wrong. That is the purpose of the Project Management discipline, to manage through all of the things that go wrong and right the ship.

I have been involved as a consultant in more HR technology selection projects than I care to count. The main reason companies engage consultants to assist with this process is because it's a big investment. Big enough that nobody wants to get it wrong. The consultant is sort of an insurance policy, the outside expert who will make sure we don't drive into the brick wall.