It depends on each case, since each type of culture offers a series of advantages and disadvantages. On the one hand, it is easier to carry out the short culture and, if there are not many embryos available, it is more likely that some will reach the day of the transfer.
On the other hand, by means of the long culture we can better select which is the embryo with more probabilities of implanting, since only those that are of good quality reach this stage.
Therefore, each patient will be more interested in one culture or another depending on the characteristics of their case.