I don't often talk about what I've not done myself but in this case... Retiree, my opinion is that you could stand to improve a few things. For 3kW I would veg longer and use much larger containers, like 15-30 gallon totes. Experiment with let's say, 10 gallon and double what they have now, and finish veg two weeks later.

Otherwise, your yield of of 3 oz in a 5 gallon pail with a 5-6 week veg is better than what I'd expect to get with a 400 watt and 2-3 weeks less than my normal veg time. My recent grow went nine weeks veg and twelve weeks to bloom to finish.