Is spending in projects constant throughout the project?
Generally in initial stage of projects (design and requirement phase) the cost is very less (as you require maximum business analyst and architecture), but as the project proceeds cost factor starts increasing. The cost is maximum in the coding phase (this is where you need programmers, project leads & project manager). After that when the project is in testing and acceptance phase cost is less as we will require only one or two programmers for removing the bugs, than the whole team.
Figure:-Graph showing cost variation in project.