Not only does it depend on the project, and the team/skills, it depends on the organization. I’ve worked in pretty lean organizations with a solid/experienced team and would say things got done in 50% of the time as above. As a consultant, I might do the work in 1/3 of the time.
If you track things out, you might be surprised to see how long “actual work” takes, vs. time spent talking about it, meeting about it, planning the planning process for it, tracking it, etc.
In a larger organization with a big team and management/review structure things could easily take 200%+ of the above.
I recall interviewing once in a large multinational organization and presenting some work my team (of 3 including myself) had done. The interviewers commented that the work was great and asked about the other teams involved and how many years the project had taken. They were shocked when I told them that we had done everything from product planning, to design, development, marketing, packaging, etc. from initial plan to retail in a 9 month window. They told me that it would have taken them 1.5 years typically using 3-4 teams (marketing, design, development, etc.) of 5-10 people each.
So… yup. It depends.
R