Yes exactly, with the DCAing method you can start from investing a smaller amount then you keep on maintaining the standard amount and sooner you might get another opportunity which might make you increasingly increase the amount which you allocated to your investment (from investing $15 to investing $20 or $30 in Bitcoin) and other things are it doesn't matter how much you put monthly what matter is how consistent you keep on buying. When you bitcoin of $30 every month a year is =$360 and during the year there might be a month when you will allocate more than $30 that's why you have to keep on buying so you can meet up.
Yes, and investing money regularly instead of just saving it in the bank can potentially lead to higher profits. By using the DCA strategy of investing $30 every month, you can earn a profit on your investment. The same example you have given, if you invest $360 in one year using DCA, it’s difficult to predict the value of the investment at the end of the year. But it’s possible that you could earn a decent profit.