In the end, it comes down to delivery.  All the other six onboarding landmines ultimately hurt delivery (Organization, Role, Personal, Learning, Relationships, Adjustment).  The 40% of leaders that are pushed out, fail, or quit within 18 months fail to deliver.

An advertising agency was two hours late for a major presentation in London.  When they finally showed up they explained that they were delayed by fog at Heathrow airport.

Using fog at Heathrow airport as an excuse is like saying there's traffic in Tokyo or power outages in Baghdad  Of course there was fog at Heathrow airport!  The issue was that the agency didn't account for it.

Deal with the landmines

Similarly, in many onboarding situations, there are going to be organizational, role, personal, learning, relationship, or adjustment risks.  The issue is not these landmines.  The issue is how new leaders deal with them on the way to delivering what is needed and expected.

Bottom line, figure out the barriers to delivery early on.  Mitigate them.  Then, inspire and enable others to deliver the right things at the right time in the right way.