I use the same wifi analyzer to tune my network. I select the channel that has the least interference from other networks. You can see the networks nearby, the strength and the channels that they are using.
I select the channel that is least busy. I've found that shifting to another channel range (which is what you're selecting) makes a difference, so it is useful.
As Bob mentions, the emissions from household items can interfere, from temporary emissions like microwave to longer term ones like phones. I have an apartment, so it can be critical to maximize the wifi connection. As of right now, I have twelve networks active very near me. The bulk of them seem to be overlaid on the default, so I avoid that.
It is one of the things you can do to tune your connections, but if chosen correctly, it can help.