what made DVC practical for use was primarily the amount we saved on food. we are not foodies so after DVC we would only do maybe 6 character meals a trip and the rest of the time do simple food in the villa. Once kids are "adults" the savings are even more noticeable. We would do 10 to 15 days and do a lot of splits with studios at the beginning and or end.
do not worry about having the "right"number of points going in, since transferring in and renting reservations are pretty easy and of coarse you can always buy more points