I want to reserve this post to address an argument brought to me that is supposedly in defense of shield toggles. I want to remark that this argument has nothing to do with the stated purpose of shield toggles or the rest of that section in the OP. It's also been phrased pretty much ad verbatim, by multiple people in the same way. This makes me think that this argument did not originate from them. I'm not too involved in the rest of the community, so I figured I will share this answer here.
The argument that's been brought up is that this is just an "APM-intensive mechanic to give you minimal gains" and we don't have to worry about it. So, without addressing the truth value of this argument, I want to ask, even if this is true, why exactly is this mechanic being kept? Shield toggle could award you with a grand total of 1 energy per second and it would still be something you should get rid of. The argument I made was against the principle of this mechanic even existing. As I said in my original post, STS was removed from caps for being too APM-intensive so I fail to see why snubs should have something like this.
Now I want to address this argument about "minimal gains". It's really hard to tell exactly what people mean when they write like this: Do you mean that the net gain to your PvP situation is not meaningful? Do you mean the powercore gain is insignificant? From further questioning, the general sentiment I get seems to be the latter, that the effect on the powercore of shield toggle off is rather unimpactful. It's not. I will do some basic calculations using numbers from FLStat of LF-VHF ships regarding powercore regeneration and powercore drain, but I will exempt certain outliers (Anubis, Shihai, Maintenance/Mining/Scanner Drones) because I did not check them before, and cannot check them in-game at the moment, to accurately confirm certain things.
LF: Powercore drain -> 510 | Powercore regeneration after drain: 905 - 1050 | Result: Gaining 48.6% to 56.35% of core regeneration from shield toggle off
HF: Powercore drain -> 305 | Powercore regeneration after drain: 920 - 1120 | Result: Gaining 27.2% to 33.2% of core regeneration from shield toggle off
VHF: Powercore drain -> 380 | Powercore regeneration after drain: 950 - 1070 | Result: Gaining 35.5% to 40% of core regeneration from shield toggle off.
I would argue these numbers show that it's very impactful. It is true that the net gain to your PvP situation isn't very high from toggling it off and in most cases I would say it severely harms you. This is because shield regeneration values are a lot more valuable than even the gain in powercore from shield toggle off (this requires more analysis in this post to prove it, so I will just leave it as it is). However, arguing that there is almost nothing to gain requires some stretch of the imagination.