On the flip side I am often glad that I only prepare and don't jump into coding/doing. It would take me a lot longer to figure out that it was a bad idea if I am coding and not sketching out the full thing. I have a whole blog of http://ideasfrommydreams.blogspot.com/ such ideas that upon reflection are usually not that great.
Problem with that approach is a small idea that isn't that great can evolve into something a lot better while you're working on it (esp. with casual games) - an idea that only exists on paper isn't going to do anything.
Pretty neat, specially for us on the last leg of development which seems to be taking forever!
Been blogging about my 2d mmorpg for android here: http://developingthedream.blogspot.com/
Thank god it's not just me! I always found finishing a game to be extremely difficult - to the point where I have stopped making them all together. After being done with 90% of a game you still seem to have 90% of the work left to do. kylemaxwell is right that this happens with many endeavors but it seems to happen with games the most.
This reminds me of the Pareto Principle :
It takes 20% of the total time to reach 80% of the project.
It takes the other 80% of the time to achieve the remaining 20% of the project.
https://secure.wikimedia.org/wikipedia/en/wiki/Pareto_princi...
One of the most important thing I've learned.
Oldie but a great read for anyone who's working for themselves, doesn't have to be specifically with games it's the same for weekend projects & anything else too.
This is true for many, many endeavors.