Slices selection in pyradiomics

I combine the use of SimpleITK with PyRadiomics to extract radiomic features. The thing is, I have a large number of cases, so for the GTV, I take 3 slices above and 3 slices below. Otherwise, the extraction process can take hours. However, I don’t know exactly how many slices I should take above and below in order not to lose information. Has anyone else faced this problem?