In my experience, the bigger the project, the bigger the multiplication factor. On a big enough scale, multiplication by 2 might be not enough. Most often I fin

In my experience, the bigger the project, the bigger the multiplication factor. On a big enough scale, multiplication by 2 might be not enough. Most often I find that implementation times can be estimated quite reasonably, but time for testing, documentation, team-coordination and communication are not factored in properly.