Why are you assuming that they are testing one scent at a time? You can test as many candles for wick size at the same time as you have room for, as long as you are pretty organized. Also, once you are experienced in candlemaking and know your wax pretty well, it doesn't take three months to nail it. For an 8 ounce jelly jar, I can wick a new FO in a week even with somewhat limited burning time only after work. If the stars align properly and I'm only testing for wick size, I can do it in a long weekend.