For any ability that isn't exclusive to main slots the strength of the effect is measured in ability points, often shortened to AP, with more points meaning more effect. An ability a main slot is worth 10 AP and each sub slot is worth 3 AP, so main slots are significantly more impactful. So in the case of testing an insanely high amount with the 3 mains 3 subs that I had in my tests, that's 39 AP of sub power, 30 of which were coming from just the main slots (Though I wouldn't actually recommend a build like that, it was just for show. The additive benefits of each ability get weaker the more of it you wear so a variety of abilities is generally best). A general way to look at it is that 3 sub slots is about equal to 1 main slot, since 9 and 10 are close.

true but curling bomb cooking is actually pretty threatening as a pure bomb too. partially because it can trap slower weapons before exploding and paints a ton. it's such an interesting sub.

Think you meant ninkbrush, nocto has beakon, nink has mine

main issue is you gotta move forward to set it up and then back up, doesnt work super well outside of wipeouts and then you have to make sure the opponents dont go through those mines while getting to you.

Definitely I'm crazy And I've been using it since splatoon 2 week 5

To make highly technical weapons work at least in my experience you have to get deep into the details on what makes that weapon unique and make the most of that. In the case of tri stringer I know most players see its crazy turf output and potential to play like a charger or other backline weapon thanks to its range, but I don't often see stringers get bold with the close range tap shots or get creative with arcing shots over terrain as much as they could and other things like that, and those traits paired with the more standard playstyle for the weapon is what makes stringer special compared to other options. To find long term success and enjoyment out of weapons like that you have to have some intrinsic motivation to continually experiment with new ways to utilize the weapon and essentially pioneer the weapon beyond how most people see it. Probably my own most relatable experience with that was when I used bloblobber for a long time in high level competitive play. Most people see the weapon as a passive weapon that sits back and spams paint all game, but I also was fascinated by it being the only slosher capable of killing in one slosh and that motivated me to push an aggressive side of the weapon that threatened fast kills off of one-burst shots but that could also pivot to that passive painting playstyle whenever necessary, so the end result was my bloblobber play being far more flexible and consistent than everyone else's. Making that work consistently is extremely challenging though and takes a very long time, which is why I think you have to keep yourself motivated with new ideas to try as you keep practicing since results won't come for a while.