I regularly hit this with some of the sativas on relatively low wattage lights (250-600), but I think it has more to do with the bloom time (12-14 weeks) and genetics than any magic technique.
The hash plants on a REALLY good run rarely top .4 to .6g/w now that I look over the log.
.5 g per watt seems to be norm for alot of people, ive seen 1 gram per watt purple kush sog but that is running super high numbers and a lightfoot print of 6x6 for a 1000w bulb.