Costs can easily inflate for MEP (mechanical, electrical, plumbing). Contractors go to suppliers for pricing, suppliers add contingency costs, contractors add their own contingency, and the cost can inflate enough to kill the project.
Image c/o: KK Law
Advice
Example of a mainly successful project: Brock Commons — involved a high degree of collaboration: Integrated Design Process — design offered 3-4 options for every connection, which every stakeholder vetted — invested in building a mock-up, where many problems were solved in advance of construction — the design worked with standard panel sizes
Advice
Tolerances are different for each different trade. Mitigate potential problems with communication in the procurement phase.