400w hps compared to 1000w hps yield difference

That is true for old generation HPS, it follows a rule of about 1g dry plant matter per 1 micro mol.
Newer generation lighting options can provide 60% more.

Adding more plants with shorter veg is one option, fewer more mature plants is another. I prefer the weed off the more mature plants.
The important thing is how much of the light falls on the plants and how much on the walls and floors when it comes to low light options.
A 400 in a vertical grow can give a horizontal with 600W a good run for it;s money, because the reflective backing is right behind the plants, it is like having lighting from inside and out.

any motherfucker claiming 1.6 per watt better post some impressive pics or im calling bullshit= im calling you out anc show me your 1.6 + pics or you are full of shit. You shouldnt do stupid shit like posting fake numbers, it ,makes you look childish.

You will get a little more weight but for sure denser buds I did 6 plants on a 1w grow then I did 6 plants in a 2k w grow nownim doing 1 light per plant using LEDs.

1000 grams/1kilo on a 1000w/1kwh HPS is hard. 400g on a 400w easy. In my opinion. A lot of good points in here

Cannafamilyfarms or follow on Instagram. That's my family and they get 2.5-3lbs per light. That's 1.5 grams per watt. About 1500grams per light per table packing the in and scrogging at 3ft

Or try boxing your light in with walls of plants and scrogging. Adding 4 more dimensions can potentially triple your yield. 5 Scrogs per light would not waste any lumens.

Ok, i'm hard after seeing canna family farms pics.

Here's a pic of me doing 8 plants under a 400 watt.plus a 150 watt but it only worked the first 2 weeks of flower got dense ass buds only vegged 30 days got 2and a half zips almost off every plant so 400 watts will do good a lot if you care for your plants