Getting collaboration when you really need it, when the interaction can add value is usually at the beginning of a project. The closer you get to the completion of the project, the more the parameters tend to be set, it is the detail that changes, a much more mechanical process of executing what has been agreed through the early collaboration stages when things were more flexible and creative.
However, it is often towards the end of the project, particularly when the outlook is positive, that it becomes easier to attract those who may have been useful at the beginning, but whose contribution later will only cause hesitation and changes that result in a slippage of delivery dates for the project.
Of course, the worst “collaboration” is when someone exercises institutional power after the point where it is useful.
Towards the end of a project, it is co-ordination and project management that is needed, not collaboration, which should have happened at the beginning. How often it gets all arse-about!