There are various ways to calibrate 24, 96 or 384 channel instruments, but many manufacturers rely on gravimetric-only measurements to provide an average result. The problem with this approach is that it can conceal outliers. Here at INTEGRA, we use a hybrid gravimetric/photometric method, which not only assesses each channel individually, it also more closely resembles the results you can expect in your own lab.
Any questions? I'm happy to help!