I guess it depends what you are doing at the time, if you are tuning the MAF and injector scaling, then fuel trims are imperative. Check the video and EVOX pdf guides here, on what to log:
http://www.evoscan.com/helpdesk/knowledgebase.php?article=5
http://www.evoscan.com/technical-vehicle-manuals/16-understanding-vehicle-efi-systems
http://www.evoscan.com/helpdesk/knowledgebase.php?article=5
http://www.evoscan.com/technical-vehicle-manuals/16-understanding-vehicle-efi-systems
