What role does cross functional teams play in project efficiency and can you please provide examples?

What role does cross functional teams play in project efficiency and can you please provide examples?
Cross functional teams usually consist of experts from various parts of either the business/company or larger domains (if you have subcontractors). Having experts from the relevant departments (e.g. commercial, legal, finance, HR resourcing, supply chain, purchasing, engineering) can significantly improve the efficiency of teams and projects. Something that your team don't do regularly could easily take you more time, then employing an expert for a few hours. A good example would be procurement. there is usually a lot of paperwork to get signed off before purchase orders (or the equivalent) are approved and items ordered. I usually delegate this task to an engineering administrator, knowing they have the knowledge to get the right part at the right price far more efficiently that I could. Another example could be employing a subcontractor or engineer from another part of the business to resolve an issue, they may well have seen before on another project. It could take weeks for my engineers to identify the problem, because they may not have seen it before and will have to start from scratch to locate it.