I haven't found that measurement used very often in my exp for the fact there are to many variables. I think to get a better ball park figure you have to have some more specific questions, size of space you have, amount of lights you can use according to your space and venting abilities and your grow medium, meaning are you using soil, coco, RW, grow rocks or what. You may be able to put 4 5 gallon pots of soil under a 1K taking up a 4x4 area and veg for 2 months and flower for 2 months and pull 12 to 16 OZ's which would be 5G per wattage of light or you could put a 4x4 ebb and flow table under that same area with 20 to 30 plants and harvest 1.5 LB with only 1 week of veg time. Methods, experience, strains and more determine the outcome.
Perhaps you need to think about your goals, energy level and ability to commit to a project weather big or small in all of it's different facets.