[iKnowKungFoo]

For me, it depends on how many companies are hiring and who they are. I left my previous employer just over 2 years ago, found another that was hiring that evening. Once I realized I knew some of the people there, I didn't bother looking elsewhere since it was apparent they would give me an offer.

Previous to this, I tried to interview with at least three companies and have two offers before I decided. However, you have to tell any company that gives you an offer that you have others lined up for interviews. Try and figure out how soon they need a reply, but don't drag your feet. If you wait too long, they'll usually have someone else waiting in the wings.