I am pretty sure that I know just what you are trying to do. And, very possibly the "why" as in why you are trying to do it. I am working on the same sort of project but the plants are growing inside and I can test how well I am doing by putting one or two clones outside to see how well it is going in sunlight.
so after a bit of testing, i realized that my strategy for getting fewer thicker branches isn't really working, i kept on cutting the heads off the tallest branches thinking it would cause them to grow larger as opposed to long and thin, instead now i have even more small branches...
When the tips of the growing branches are cut off the plant will send the hormones that cause that branch to grow to the next available growing tips. Since those tips are already getting their fair share they will now be getting even more. That helps promote the growing of more new dominant stems which is what you are trying to avoid. The plant will not increase how thick the remaining branch or stem is fast. The stem will thicken up a bit as part of the natural process of growing but not as fast as you need.
i'm trying to get thick stems, and a less bushy plant, i already do LST and supercropping, but my plants are still extremely bushy and i don't like so. i'd like my buds to be bigger as opposed to many small buds
Thick stems and "a less bushy plant" are not necessarily the same thing nor related. Maybe they are, but it probably is best to look at those as two separate goals at first. Once you accomplish both goals then join them together into the one goal.
The Low Stress Training and the Super-Cropping are methods of changing and/or increasing dominant growing tips on branches with the intent of increasing the number of potential bud sites which is not what you are looking for. I figure you are looking for a limited number of bud sites but want the buds at those sites will be huge and heavy. Or, are you looking for something else??
what other technique can i use to achieve this? i was thinking maybe cutting all the new growth would trick the plant into putting all it's energy in the already existing branches, can this be possible?
Changing the fertilizer blends will help. Find blends with a good amount of calcium and silica. Or, add the calcium and silica to the fertilizers you are already using. That will help produce the types of stems and branches you are looking for. Then feeding with flowering fertilizers and giving a bit of a boost with the appropriate "finishing" nutrients about half way though the flower stage will help produce those big and heavy buds you want.
Growing the main branches out as long as possible and then cutting off all but the first 2 feet coming from the main stem will leave some very thick, strong & woody branches. The big problems I can see are the timing since you are growing outside and cannot control the light schedule.
If you find a plant that is growing the way you want during the vegetating stage then best to take several cuttings, rooting them, and starting a small clone farm for the next year. There is no guarantee that any other seeds from the same strain will end up giving you a duplicate plant. Even seeds from the same parent plant that produced the first seed you used might not give you another plant that grows the way you want.
I use silica AGISIL 16 for strong branches I get BIG BIDS I've ALL the branches but I also train them
good luck