Angle
I think many head out using what they think is a high angle stroke, but by mid afternoon form, endurance and mechanics break down and the stoke evolves into a lower stroke, but I’ve never made a concious effort to grab or switch to another paddle to mimic a stroke.
Best thing to do
is get one adjustable from 198 to 250 cm. Then, on a closed and measured coarse, paddle at various lengths. Vary about 1 mm at a time and record your times each run. The run with the lowest time will be the most efficient setting for you. But maybe not the most comfortable. The experiment shouldn’t take more than about a paddling season to complete.;))
That’s exactly what I did 
tools and techniques
I personally feel that there’s a right tool and technique for the job at hand. So i practice both high and low angle techniques with the appropriate paddles.
In my opinion, paddlers that only do one kind of stroke and use one kind of paddle may be selling themselves short.
If i’m going for long distances or long trips i can go farther with less effort with my low angle technique. If i need powerful strokes and manueverability, i feel that my high angle stroke is key. I think it’s pretty simple.
I have to add that i do not agree with some statements like “go with whatever feels best”. For most people, good technique does not come naturally, whether it’s high or low angle. Torso rotation for me did not “feel best” at first. I just wanted to use my arms. I’ve had to work at it, but it’s worth the effort.
Overthinking
I think everyone is over thinking this. My style is my style, which has been adapted over many miles, hours, boats and equipment. I don’t overthink and switch paddles or angle to diversify my stroke. Conditioning, proper mechanics, torso rotation, contact with the boat and boat control have more to do with the breakdown of a stroke vs. which style.
I prefer a high cadence and I’m physically strong and conditioned so I use a shorter, larger blade paddle, which lends itself to a high angle style. I don’t think this makes anyone a less diverse paddler. I’d be lying if those of us with a high angle stroke didn’t break down after a 20+ mile day and adapt to a lower style, but the torso is still involved with the stroke.
In the thousands of miles I’ve paddled I’ve never been with anyone who has said “wait while I switch my paddle, I feel like paddling with a low angle stroke for a while.” I’ve also never heard of anyone making a concerted attempt to practice different styles. Practice rescues - yes, rolls - yes, launching and landing in surf - yes.
I am like Grayak
When I am racing or race training it is high angle with a wing.
When I am just out for a joy paddle it is a low angle with a euro paddle, but then every so often I will throw in a sprint, and immediately change to a high angle with that same euro paddle.
Cheers,
JackL
If I am using a GP
I adjust the angle all the time depending on conditions and what I want to do and almost never change paddles. Wind come up? I lower the angle. Want to catch up to someone? I raise the angle and increase the stroke rate. Want to move along at a moderate pace and talk? Go with an in-between angle. Going through a weed zone? Lower the angle a lot. I do the same with a Euro paddle except if the wind really comes up I switch to a GP.
i don’t think anyone is "overthinking"
it.
the average paddler paddles with a low angle stroke.
When a paddler starts racing or wants speed it is a no brainer. He just has to paddle with a high angle stroke.
To switch from a low angle to a high angle it simply takes practice.
As simple as that.
“Over thinking” doesn’t even enter into the picture.
Cheers,
JackL
Depends on conditions as well
If i am going with the wind and surfing waves or going with the current, i find i do better with the bigger bladed, low angle paddle. When heading into the wind i find the big blades can take alot more effort to push into the wind constantly, and i will usually go with the smaller bladed, lower angled paddle. Flat water will be whatever i feel like that day.