Need opinions

I've been growing on and off for years. Always used coco, canna A and B, boost ect. I top and lollipopmy girls and always thought I've been doing everything right but heres my problem...
I'm growing in 20 liter pots with coco and perlite and at the end of my harvest I always get roughly 2oz (sometimes a little more) a plant. I've never got much over yet I read peoples posts and they talk about the huge yields they're getting, twice the amount I'm getting at least...is this people blowing their own trumpet or am I missing something? One thing I may be doing wrong is I'm not watering g so theres a run off, is it something so simple like this that I'm doing wrong? Could simply adding more volume of water and nutes solve it?

What light do you have?

Not watering to run off could lower your yields by affecting nutrient uptake but if your plants look healthy I doubt that’s the cause. How long do you veg for and how big are your finished plants? If you’re getting a couple ozs off a 12” plant you’re doing alright. Have you thought about trying a dwc buckets or nft? Both are cheap to setup and might work out better for you. Getting rid of the medium makes thing easier imo but I’m a hydro guy so I may be bias

You'd need to tell us what type of light you're using, how long you're vegging, what your temps and humidity are like, air flow and someone may be able to help.

I have 35 ladies in 20 litre pots in room 1 under x8 HPS. Temp is mid to high 80's during day and atm high 50's low 60's at night when lights are off (its winter atm and I'm trying my best to warm room up when lights are off)
They are about 5ft tall, supposedly purple gelato however I'm sceptical as they were cuttings off a friend of a friend x10 other friends.

They've been vegged some for 4 weeks. I do have 7 in smaller pots that were vegged for much longer (8 weeks) and to be honest they're better than ones in bigger pots but shorter veg time