I flew United for the first time in a while a few weeks ago.

My itinerary was as follows:

Outbound: BOS-SFO-SEA

Inbound: SEA-ORD-BOS

When selecting seats for the BOS-SFO segment, I found myself stuck in the back. I was resigned to this until the gate agent made an announcement that they needed 2 people to give up their 2 seats together in exchange for an exit row. My gf jumped up and ran to the gate agent before I could turn around. Success, I got E+ on the transcontinental flight without paying. On the SFO-SEA leg, I was stuck in the back but I didn't care because that flight is 1.5 hrs.

On the way home, I had picked row 13 on the SEA-ORD leg, which I was told was regular economy. Fine, I was resigned to my fate of being squished. Sure enough, I get on the plane, find my seat, and low and behold, it was E+. I didn't pay for it (I was squished in the back on the ORD-BOS leg, but once again, 1.5 hour flight so I didn't care).

Now, in the weeks before my flights, I logged on to ua.com and saw the option to purchase E+ would've cost me about $100 per person RT. I kept saying it wasn't worth it and didn't pull the trigger, so needless to say I was surprised that half my segments, I got it for free.

So this leads me to wonder if I fly UA again, should I ever entertain the possibility of paying for E+ if I basically have a 50/50 chance of getting it for free? Is this a common occurrence, or was I just lucky?