Especially if you live in a country with terraced housing.
I changed mine from the default 11 to 7 and my bandwidth shot up from about 5mbits to around 15mbits.
I guess my neighbours either side had both left theirs at 11.
This is good advice, however be warned that the channels actually overlap! This means that, for instance, channels 6 and 7 will still interfere with each other(thank you, IEEE). The three standard channels that don’t overlap are 1, 6 and 11.