Certainly. While you could work out exactly the number you might need, a reallocation could get you (or help you). These are some of the reasons I said a 3 year cycle is tricky and why I've said in the past I think every 2 years is a better plan. It is more forgiving in these situations allowing some flexibility if the members plans change or the points costs change for any reason. While I don't mind having extra points, I'd rather be under and have to pay cash for a day here and there or rent a few points for transfer, than lose points routinely.
I think point reallocation is the low risk. The bigger risk is that you switch seasons ever so slightly because the kids' vacations switch. Or you planned to fly in for Saturday to Sunday ever three years, but suddenly life has you flying in Sunday instead of Saturday and leaving Friday so you don't miss the kid's soccer games.
If your kids are say five when you buy in, you'll take four vacations on an every three year plan before they go to college. And then chances are good you'll need a different number of points when your kids are adults - more for their partners - or fewer because of less kids.
Life changes too fast for DVC ownership with an every three year schedule - at least mine does - and you can't build in as much flexibility with banking an borrowing as you can if you plan on every year or every other year Disney vacations.