Education costs — especially for higher education and study abroad — have historically risen faster than general inflation, which means a plan built on today's fee numbers will likely fall short by the time the goal arrives. This makes it one of the clearest cases for starting early and letting compounding do the heavy lifting over a long runway.

Because the goal date is fixed (a child doesn't wait for markets to recover before starting college), the investment approach typically front-loads equity exposure for growth in the early years and then systematically de-risks into debt as the goal approaches, so a market downturn in the final year doesn't derail years of disciplined saving.

It also helps to plan in stages rather than one lump figure — school years, undergraduate study and postgraduate or overseas study each have their own timeline and cost, and can be funded as separate sub-goals with their own glide paths rather than one undifferentiated pool.