In theory, no, in practice, yes.
People remember bad experiences very well. If I have even one experience of congestion in the period of a month, I am going to remember it and complain about how I need more bandwidth.
Rule of thumb, if you are inconvenienced for any reason because of lack of bandwidth, you don't have enough.
Just wait until you have several computers on your network that all attempt to download a 1GB Team Fortress patch at the same time, while you're in the middle of <insert something important that is latency sensitive>