Ganglion INA and ADC Gain levels for EEG

I've been looking into getting a Ganglion board for EEG research. One thing I wanted to get clarification on for the hardware design was the mid-range gain, which I understand is set at 51 on the INA. Historically for EEG, I've seen designs that are into the 1000's for gain at this stage and even the example circuit for ECG in the datasheet has the gain set at 100 - ECG signal are far greater than EEG. Does anyone know why the gain was set at a conservative level when the AD8237 is capable of much more? I know there are some limitations on analog input voltage for the MCP3912 so was it around concerns of going beyond operating ranges on this ADC? or was it a tradeoff around noise and the fact that the ADC is capable of recording amplitudes at this level for EEG? Even if you max out the gain on the PGA on the MCP3912 it's still way lower than what I've seen before - might be because these previous designs are older, just wanted to see if anyone could provide insight. Thanks