In principle, the size of the oven should fit the size of the chamber. A system 2 XL with a maximum mould length of 2 meters requires an oven for parts up to two meters, otherwise large parts cannot be tempered. Depending on the resin used, this can lead to important strength problems and brittleness.
In order to avoid using a large and cost intensive oven for small moulds, it sometimes makes sense to purchase a third smaller oven for this purpose.