My $0.02 - if you want to fix your swimming, take time off run and bike and just swim for a year. It would be unlikely (not impossible) that someone could go from a 1.45min/100m swimmer to a 1.24min/100m (FOP) swimmer by just swimming 3 x 3km a week and running and biking at the same time. Those 50+ little variables take a long time to develop and incorporate into your stroke.
While for sure there are people that can achieve this, I can guarantee that the vast majority of adults who have achieved around 1:45/100m won’t be able to jump to 1:24/100m even by going pure swimmer. I’m very similar to those stats, and I’ve gone through injury periods where I swam a lot (north of 20k), videod myself every week, and did a wide variety of workout speeds, and still was barely faster than my original plateau speed. I’ve honestly never come across a perennial 1:45/100m adult swimmer who’s been stuck there for like 2+ years, suddenly go swim a ton, and come back at 1:24ish pace for the same effort. Never. Whereas I’ve def seen kids and fairly new adults swimmer improve that much, with less training.
In contrast, when I do that kind of isolated training on bike or run, the results are much more noteable. I do think it has a ton to do with the high resistance of water, and the difficulty in improving technique/drag and even fighting against suboptimal body types (people can deny it all they want but having advantageous body types in swimming is absolutely enormous. Things like large hands, long arms, short legs, and even more body fat in women, help a ton.)
I do agree that video analysis is really important and helpful, and it’s always shocking how your video does NOT look like the way you think you swim. For me, I feel mentally like I’m so smooth and non-jiggly in the water, and then on video, there’s so much more extra motion than I realized. When I improved it I was amazed how still my entire body has to be in the water to just look like it’s moving smoothly. Similarly, there seems to be almost no limit to how wide I can make my stroke - it never looks ‘too wide’ on video. Even when I’m splaying it to what feels like ridiculously wide (like farrrrr past my shoulder width), somehow on video, it looks fine, and even better than when I swim with what feels like a reach that’s ‘in-line with the shoulder’ which invariably looks too narrow.
Sad part for me though, is that at my plateaud level, the video analysis hasn’t led to meaningful speed increases. A lot of the stuff I do that looks better, either doesn’t make me go faster anymore and in fact makes me go slower. (Like looking super-smooth and still in the water, or reducing the width of my 2-beat kick so it’s nearly imperceptible, both of which slow me down a good deal, even after tons of practice - I STILL practice these things because they look so good in the water, but stopwatch don’t lie!) And the things that I want to fix the most, particularly EVF and pull path, are the hardest to fix for me. I seriously strongly suspect without the physical hard training to be able to pull at FOP+ speeds, you can’t get that pretty EVF.
The video helped me a ton with speed improvement though, in my beginner-intermediate phases of swimming. In those phases, the errors are so big but weirdly still so hard to realize until you see yourself doing it, that when you fix them, your speed goes up a lot.