I tried a Target Practice event in either the Constitution Hall or Downtown West area (I forget exactly which) and I ended up not completing the final round. However, I was still rewarded with the full XP reward that I should have gotten for completing all 4 rounds, even though I got the "Target Practice Failed" message. I then went to Downtown East and tried to replicate the result. What I found was:

- The XP/reward is only given if the player completes at least 3 rounds
- The event REMAINS active, meaning a player can repeatedly access it and get ~5% XP to their next level each time
- This can apparently be done at ANY Target Practice event.

Since it takes ~1 minute to finish 3 rounds and then fail the last, it would take about 30 minutes to go up a level (figuring in the event stopping and having to travel to another a few times) without any actual combat happening or missions being undertaken.