A lot of times what it likes in static condition will change once you do a sweep. We have a load based dyno, and keep at a set RPM, and make adjustments based on load. You can only do this realistically up until 4500 rpm or so on a turbo car, and do the top end in sweeps. We always do road logs after it's been on the dyno anyway. I would say if you have a good tuned base, logging on the street is the best, although it's not particularly safe, unless you're prj that has access to an airport strip.