I wish i could tell you that ideas don't matter and it is execution that makes a difference. Then I could show you all kind of data to prove my point. But that's not what I am here for. Actually I can't even give you my own example because I cannot speak from experience.
I do have lots of ideas and they come and go everyday. I do not act on all of them. If I had taken the time to work on each and everyone of them, by the power of statistic, I would have been very successful by now. If I have 20 ideas for a website/service and I act on all of them, there is a chance that one of them will be successful. Now let me repeat this with a slight change. If I have 20 ideas, and I allocate enough time and resources to each and everyone of them, one of them may become very successful. Now you see there is a difference here. Time and resources.
So how much is enough time and resources?
When I was looking for my first job as a web developer I did not have a portfolio of my work. Well I didn't work on anything so there was nothing to show. So I decided to start a few projects that I can show off on line to impress my future employer. I settled for a tutorial website, which has now been yanked off the web. I spent a month writing it and it was very basic. Just some php files with no framework, and a very very complicated
.htaccess file. 2 months later I had lots of content and it was ready for show. So it took me at least 3 month to get this very simple project up and running (and I did get the job). How long would it take me to make 20 projects.
3 month * 20 small projects = 60 months.
Thats 5 years to get 20 small projects, and I am not taking into account that I have to maintain each one of them. In reality the time spent per project will grow exponentially and I will be overwhelmed very quickly. Imagine if Jeff Bezos had to work like this, would Amazon become what it is today?
How much do you value your Idea.
Now if it is just a numbers game by all means you should start as many projects as possible and hope one of them takes off.
However if you really value your idea, you should take the time to work on it. Do you have an new Idea and are passionate about it? Don't just start by coding. Do some research, make a plan, study your market. A great idea takes time to develop. We tend to use Google, Facebook, Microsoft and the such as example. But all these companies didn't happen overnight. There was a lot of work behind it, and the creators where passionate/obsessed about it.
In August 2012, I decided to take a different approach on my side projects. I decided to work on one at a time, and not to distract myself. This time i didn't just think of an idea and started coding. I took my time and wrote specs for the first time.
Nothing was left to chance, if my idea was worth the try I might as well do my best. Six month into it, the first version was ready to meet the real world. Featuritis is a very common disease but I was immune to it. Then I deployed S-crit.com a website where you can find school reviews by real students. Yes it is not the most unique idea and yes I do have a lot of established competitors (I'm not giving them a free link here). Now I am focusing mainly on this project while I still have a full time job. I will take it to the end. Either it works or it doesn't, at least I will know that I have tried every possible avenue.
Failure is not so bad.
Like I stated before, this is my project and I love it. But if it were to fail, well I move on to the next one. What I will have learned from this will be valuable. But I know failure is an option.