Once a person ennters BackTesting, assume he'll do several and let the time period remain for all the tests.
Walter Mardik commented
This is the suggestion I was looking for but ran out of votes by the time I got here! Backtester would be much more effective since I use several backtests over the same periods to see which one works the best. I thought that was the purpose of the backtester!!!! A start and end date button to the left of the new button on top of the page would be awesome.