For reading in the point data a certain maximum number of points per set is used. The size is usaly high enough by default, but it may be necessary to enlarge this size, when using very large sets. Sometimes, when there is not enough memory it might be necessary to reduce the number of points.
gr_copy -m 100000
allows you to read in up to 100000 points per set. The number of points per file is not relevant (except for some tools where its mentioned).
The programm will recognize, if the size is to small and will warn you.