In my opinion, it all depends as to how effectively & carefully the take-aways from the HR due diligence are actioned out post-merger or acquisition. The conflicts & issues may arise due to any of the following reasons:
1. The underlying assumptions happen to be at significant variance (could be due to oversight or totally unexpected adverse development) with the actual situation post-merger or acquisiton. In other words, the HR due diligence probably under-estimated the post-merger conflict areas.
2. The process ownership in actioning out the post-merger activities falling short of what’s needed.
As these conflicts are all people-centric, the key to avoid or minimise them will be having ‘seasoned’ PMI leaders.