The number of visits isn’t as important as you might think; it’s only one metric in evaluating statistical significance. The conversion rates for the control and the variations are also important. (Basically, the greater the delta between the two, the faster you will reach statistical significance.) Depending on the specifics of the hypothesis test, conversion totals ranging from 200-500 will generally net a winner. And remember, any test that produces new insights into user behavior is valuable, even if the new variation does not win.