title: Highcharts shift taking off too many points at the start
body: <p>My chart has multiple series and when I try to add a new point and enable shift to true in the addpoint function on the series it seems to take too many points off.  My requestData function runs an ajax query which hits my api and brings back data.  The initial load loads in data just fine, however after the first points being added to the series it seems to take off too many points off some of the series.</p>
  
  <p>Here is what it looks initial load</p>
  
  <p><a href="https://gyazo.com/51a2afc465f8fbb625e384e75d52b865" rel="nofollow">https://gyazo.com/51a2afc465f8fbb625e384e75d52b865</a></p>
  
  <p>and here is what it looks like after one and two requests:</p>
  
  <p><a href="https://gyazo.com/0b523e4675c681b7495a38660b4de72c" rel="nofollow">https://gyazo.com/0b523e4675c681b7495a38660b4de72c</a></p>
  
  <p><a href="https://gyazo.com/5cf7e9498ab3b34f3eaac1cf50a0bdc5" rel="nofollow">https://gyazo.com/5cf7e9498ab3b34f3eaac1cf50a0bdc5</a></p>
  
  <p>Here is my code for requesting data:</p>
  
  <pre><code>function requestData(chart1, start, devID, attrib) {
  $.ajax({
      url: 'api/MetricsAPI/',
      data: {
          deviceID: devID,
          attribute: attrib,
          startDate: start
      },
      success: function (dataset) {
          var chartSeries = chart1.series;
          for (var index = 0; index &lt; dataset.length; index++) {
              for (var i = 0; i &lt; chartSeries.length; i++) {
                  if (chartSeries[i].name == dataset[index].attribute) {
                      var shift = chartSeries[i].data.length &gt; 12;
                      chartSeries[i].addPoint([parseInt(dataset[index].epochTime), dataset[index].value], true, shift);
                      console.log('date: ' + dataset[index].epochTime + ', ' + 'value: ' + dataset[index].value);
                  }
              }
          }
          chart1.redraw();
          //call it again after one minute
          setTimeout(requestData, 30000, chart1, dataset[dataset.length - 1].epochTime, devID, attrib);
      },
      failure: function (xhr, error) {
          console.log(xhr);
          console.log(error);
      },
      cache: false
  });
  }
  </code></pre>