I am writing this post to share a recent experience I had that, to me, highlighted the importance of buying a phone that supports all possible bands in use in North America.
Recently, while shopping at my neighbourhood grocery store, I notice my phone had great coverage. On my Nexus 4, I used to get almost no coverage in this store. I took the following screenshot that shows that this is because at this particular location (in Vancouver, BC), Telus is using LTE band 17. This is a lower frequency that provides better coverage through fewer towers. The band was not supported in my Nexus 4 (admittedly a 4 year old phone).
So far, just within Vancouver, I have seen Telus use bands 2, 4, 5, 7, and 17 for its LTE network.