Time estimates are tricky

If you are an inexperienced project manager, engineer, or designer, consider tripling your initial time estimates for projects.  That’s not a slam.  It’s just that new managers don’t take a lot of minutia into consideration when developing project time estimates.  Experienced people have been through a lot of project cycles.  They have seen a lot, and the know the hundreds of little things that can bog a project down or extend it long beyond all normal estimates.  So if you’re new, triple the schedule until you know the details.