My horror story from a few years back - just a very few.
First to get broadband in the neighborhood, first with wifi. Suddenly at one point, my VoIP phone starts getting all sorts of dropout and one of the older computers always has DHCP issues on startup. The phone box seemed cheap to me and the computer was way old. Everything else in the house was just fine.
So, I'm getting ready to swap out the router, retire the older machine, yadda yadda yadda.
One thing leads to another - first, I found I never changed the default router/net name - and second, that my next-street neighbor's terrain compared to mine was helping his antenna signal - and third, that Murphy is alive and well.
We were both using the net name ACTIONTEC, we were always coming on to the same channel and many times his signal would nearly equal my own, in parts of the rear of the house nearest his.
Was at a buddy's house recently. He's on his third router. He, and his left hand and right hand neighbors - all on the same channel.
Was in Denver International Airport. Several wifi hotspots exist there - and they're all on the same channel.
Wifi Analyzer baby! Don't leave home without it!
Because sometimes, like when you're waiting to catch a flight at DIA, your wifi solution is to turn off the chaos and just use 3G.
PS - There's a whole operational theory about wifi routers should really do for channel selection on startup. And then there's what they really do.