The puppy can learn many things at once... Dr. Ian Dunbar has demonstrated this many times. However, most of us are not experienced, professional trainers (at least, I'm not), so I agree that it's best to focus on one at a time.
Having said that, I did teach my pup to Sit, Down, Come, Name, Shake, and Bow in the first two weeks, capturing repeated and very predictable behaviors. But it did take me a little longer to teach the next 5 - 10 behaviors, one at a time.