That behavior is actually somewhat new since getting into Android. Unlike iPhone, there's a new killer Android phone every few months. Since selling my iPhone 4 in early 2011, I've used 11 different Android and WP7 phones as my daily driver.

In the past 12 months alone, I've had (as my primary phone) a Galaxy Nexus, Galaxy S III, Sony Xperia S, Galaxy S II Skyrocket, and now the Nexus 4.

I plan to stick with the Nexus 4 for a while since it's really a great phone. I have been eyeing the Note II and Oppo Find 5, however.

I usually buy the phones 2nd-hand, unlock them, try them out for a while, then flip them on ebay. Amazingly, I usually don't lose money on the transaction because the phone is now unlocked and I'm willing to ship anywhere.