Integration is the main task of project management

It may seem strange to regular participants in the project community, but the question is still regularly raised on various platforms: why is this type of management such as project management needed? In particular, why is this necessary for large functional companies, which should cope with projects without supposedly "additional" add-ons in the form of project offices, project managers, etc. And is it really necessary to implement schedule network planning and calculate the critical path of the project? When I hear such questions, I usually give the following example as a detailed answer.
Let's imagine a large-scale project for the construction of an industrial facility. The total planned duration of the construction and installation work itself is 3 years or more. When summing up the results of the year and distributing bonuses, the following situation often occurs:

1. Capital Construction Department - receives a bonus for fulfilling the plan in terms of physical volume (the total amount of material sold (built, installed, etc.) in physical terms).
2. Procurement Management - Receives a bonus for executing a plan to save money for the company (through bundling bids and economies of scale, as well as through rigorous competitive bidding processes that forced contractors and suppliers to lower prices).
3. Logistics Department - receives a bonus for the amount of materials and equipment transported on a ton/kilometer basis.
4. Etc.

At the end of the year, contractors often also have a good profit, since from the very beginning they carry out the most large-scale and "expensive" work (although not always located on the critical path of the project).
It would seem that bonuses and profits are indicators that everyone worked well. But the project is often a failure, and the most common reason for failure in such a situation is missed deadlines.
Why is this happening?
In most cases, each functional service has its own conditional critical path - they set their own priorities. If you look at the reasons for receiving the above-described bonuses more closely, the following scenario is very likely:

1. The Capital Construction Department sought to increase the development of physical volumes by performing large-scale works of the second and third stages (filling the site, driving piles) to the detriment of performing the complex, delicate work of the first stage (installation of complex equipment). As a result, the work of the first stage was disrupted.
2. The Procurement Department - in an effort to lotticulate applications, ignored local quick requests from critical areas, delayed the holding of competitions, arranging overbidding. Yes, the cost has been reduced, but the lengthy procurement process has delayed the project timeline (some work is overdue by six months or more). The shift in the timing of the project ultimately led to the company incurring costs that significantly exceeded the savings from the "cheaper" work of contractors.
3. Logistics Department - transported large bulky materials (for example, concrete slabs), ignoring small equipment. As a result, there are a lot of unnecessary large slabs on the site, and the equipment necessary for installation has not been delivered - the timing of its installation has been missed.

And finally, the contractor, having completed the most profitable work for himself, transferred the main forces to another facility, leaving only a few teams that are physically unable to cover the remaining volume of uncompleted work (the contractor deliberately went to pay fines, realizing that at this stage he was unlikely to be replaced, and he could earn more on parallel "expensive" work on another facility).
One of the main tasks of the project management system is to combine the efforts of all areas, form a single critical path of the project, formulate common priorities for everyone (regardless of the wishes of individual services) and organize work on these priorities.
The main tools for this should be a schedule network model, in which it is necessary to promote critical paths, as well as the Rapid Response and Forecasting Center, which has repeatedly proven its usefulness during the implementation of large and megaprojects (see note by A. Kutuzov "TsORP is a powerful tool for integrating a large-scale project", which provides examples of how the PM Excellence company, using the CIRP and relying on the correct detailed schedule network model, helped customers reduce project implementation time).
Only if integration is ensured using (but not limited to) the above tools, the success of the project is likely. Otherwise, it is practically impossible.