Why do commercial projects finish late?

http://mcclureandsons.com/projects/Water_Wastewater/Sumner_WWTP.aspx?Returnurl=https://nyc3.digitaloceanspaces.com/us-east-1/capitalregionbuildreport/uncategorized/how-long-does-an-office-fit-out-take-in-albany-ny.html

Clifton Development Group on the four causes in order of how often they happen, starting with owner decisions made late and long-lead equipment ordered after permit.