I mean... The more soil that you have, the more of a buffer against nutrient issues. The only really limiting factor is that there is a 12 hour period that you won't be able to water them. If they'll be using so much water that it stresses them to not be able to water them during that time, then you NEED to repot. Otherwise, it's personal preference. A larger pot per plant allows a greater final yield per plant. What kind of wattage are you flowering them under?