I have now been developing websites for 20 years. In that 20 years I have seen projects come offwith very little detours or delays, and I have seen projects that never get off the ground whether it be our fault or the clients. Generally the reason this happens, fall into one of of 2 categories. The Number one project management issue I have found is communication. One party tends to drop the ball when answering a question or puts a part that is in the pipeline on hold, or just remove it from the project. This can put an entire project in limbo and in the interim, we will generally move onto another project instead of waiting for feedback or if there is a need for research, as hard as we try, it does occasionally get lost in the cracks.
The second issue that pops up is the "Dreaded Scope Creep". This can occur on the developer or the client side. The client decides they need another piece added to the puzzle, and while that piece might be important, it can cause major delays and cause friction on both sides of the table because the project overall is delayed while the developer either re-engineers, or shoe horns the piece in. OR, one of the parties see's a new feature that just has to be a part of the finished site. In both cases, a concious effort must be made to make this a seperate add-on AFTER the initial project is completed.
We have recently begun adding hard and fast dates for completion of project phases. This allows us to measure how the project is going by seeing how we are progressing in comparison to the proposal dates, and provides a tangible indication to the client how the developer is progressing. There can be monetary incentives tied to these timelines and can mutually benefit both parties. If the project is finished early, chances are the hours calculated will be smaller, there by lowering the cost to the client. Also there can be performance bonuses tied to the timeline. Either way sticking to the timeline will allow the project to be completed on before the expected date set by the developer.
In any event, both of these causes must be identified ASAP to avoid long term issues and keep both parties happy. Until next time, keep those cards, letters, and new projects coming.