Do most people renew it then at the end of the term? I mean if you are still alive in 20 yrs. would you just renew so that your loved ones would have something if you pass away?
If you need insurance for longer than 20 years (say, not done having children yet), then buy a 30 year term policy. Renewal rates at the end of the 20 years are VERY VERY expensive - if you still need insurance at that time, then you are best to go buy a new policy unless you have health issues.