I've been doing this for a while, prolly 3 years, and if you don't have an extra veg space it's good for a perpetual grow. You're definitely not going to achieve the same per plant yields as if you vegged everything then flowered. If you expect that result you'll be disappointed, it's unrealistic.
If you have a space you can veg in you're wasting your time growing 12/12 from seed regardless of what strain you grow. It's great if you like variety and want a 12/12 grow space year round without a separate veg. space.
You can definitely fill jars, but if you have clones/quality seeds and yield is the goal this is the wrong tree to bark up.
The only strains I've had do poorly are strains that don't stretch. Generally I hit 2 oz from a 2gallon (1.5 actual) gallon home depot bucket on strains that double in height. If it doesn't stretch for shit sometimes it can be as low as a half O. Which is shit by anyones standards.
I'd say by week 3-4 flower if you're not seeing good bud sets on a non-stretching plant you're better off to chop it and fill the space with something else. I've had short plants put out, but you can tell if it's going to be acceptable by that time usually. If it's not showing good signs by 4 weeks then I'm not going to risk another 4-8 weeks to find out and be even more disappointed. <--- obviously this depends on strain flower times.
If you plan on doing this perpetually you're gonna need seeds started every 2-4 weeks or so. You will burn through seed stock this way. If you're paying big money for your seeds then less veg. time equals less return on the cash you invested in those seeds.
I know there's been lots of talk about decreased quality, I haven't seen it. Some of the best pot I've grown has been this way, also some of the worst
it's just how it goes.
You absolutely need to lolipop or your yields will be fucking garbage. 25% off the bottom of the plant at least, try and do this a tthe end of stretch so nothing gets slowed down at all. Stopping that stretch is Not good.. Seems like if you don't it effects yields more than if you were to veg. and not lollipop, I could be wrong but this just seems like a general observation i've made with 0 proof to back it up.
The bottom line TLDR no bullshit: If you have a space to veg for 3 weeks you will always have better results that way than if you grow 12/12 from seed. The extra light hours will increase your yield it's just how plants work. If you don't have the space and don't want to veg/flower/veg/flower/veg/flower this is an amazing way to always have flowers in the grow area.
If you are in a 4x4 or bigger you'd be better off to get a couple 2x2's and veg instead of doing this in a 4x4.
My end heights generally around 3 +\- feet if interested.