Using Socialblade to Analyze Other YouTube Channels
If you decide to really go for it and create a robust YouTube channel with content that adheres to a single theme, you should always be aware of who else is doing the same thing. I believe that most YouTube "competition" tends to be friendly, especially since collaborations are very common and YouTubers appear to help each other out.
It is always a good idea to be aware of what other people are doing and how successful they are in doing it. Socialblade is a website that will let you peek at basic stats (among other things) that other YouTube channels are racking up. Just type in the name of the channel and it will give you a breakdown of subscribers per day and month (with averages) and views per day and month (with averages). While it might not be as eye opening for your own channel (because you already know), it is very interesting to see how good or bad others in your niche are performing.
In my case, there are really only a handful of Tubers posting regular content about filmmaking and even fewer that post regularly about DIY filmmaking. This is good for me, but also proves there is lots of room for other voices and angles, even when covering similar material.
It's always good to know how many eyeballs are watching your competition. Check out the channels that are doing better than you are. They are doing something right, and you should definitely find out what it is.