Posted: 14/10/2014 at 20:27
Sounds to me like you're doing fine if you are enjoying it. You've covered a good distance at a good pace if you exclude your walk breaks, in fact you could say you've done three runs. So I woud aim for one run at a time, and do it a lot more slowly, but go for a bit longer timewise. So instead of your three twenty minute sessions, slow down and go for half an hour, then end it there. You'll get plenty of benefit from the run, and you won't wear yourself out. after a few of those, go for forty minutes, and build up (if you want to).
Beneficial? Depends what you want...long term fitness? A fast 5k time? Ability to run long distances without stopping? Weight loss? Whatever you want to do you appear to have got off to a great start, keep it up!