GSAS: Rod Hill and Ian Madsen VCT data collection
If you do have a choice of data collection strategies for XRD - use variable count time (VCT)
Commercial vendors partially to blame for only having obsolescent data collection options in their data logging software.
Still may need to play with weighting of histograms for “fine” control of the combined refinement.
VCT Fortran Source Code with references is available:
http://www.ccp14.ac.uk/ccp/ccp14/ftp-mirror/csirominerals-anon-ftp/pub/xtallography/