One may be a mid large wing.
A midlarge wing in 205 is the same shaft as a mid in a 210cm.
The blades are 2.5cm longer on the midlarge.
As for wives tales about where to hold the paddle, just that.
You will find your own natural arm width.
How close can you hold the shaft to the paddle?
With my current extreme short experimenting, the outside of my hands are only 4 cm from the beginning of the blade.
Paddle length is all about gearing, as in setting your cadence, and has an inverse relationship to your height and reach.
At 200cm paddle length, my cadence is the same as my shorter partner at 214cm.
I can quite happily paddle down to 195cm and if struggling upwind, this length feels magical.
I'll stir the pot again on this issue and outright state that every paddle formula out there is bunk.
The only thing that matters is that the length that you use with the shape of blade you use brings you into your paddling cadence window that is efficient for you.
For me being tall with a shorter body and longer limbs, my paddle is very short.
The sweet spot for me is appearing to be 197 to 205, depending on conditions.
195 is great if you are bashing upwind at 8kph.
197 has a more solid catch, catches runners well, but can spin out on continuous flat water grinding.
200 is a good all rounder. good acceleration and still good on the flat.
205 works well if it's fast downwind with easily linkable runners.
At the moment I am liking just leaving it on 200 for everything as I know it is not far from the best in most conditions.
These lengths refer only to the particular paddle shape that I am using.
But for sure:
Paddling along at 40rpm is NOT efficient in any conditions.
Getting he correct paddle length will enable you to do a full length stroke at your efficient cadence.
In the end, that is all that matters.
Your technique will not look the same as the next person, as differing body shapes using a differing paddle length will just look different, but what matters is that the paddle is facing the forces in the right direction in the water and turning over at a speed that suits your own physiology.
Follow the path of the independent thinker. Expose your ideas to the dangers of controversy. Speak your mind and fear less the label of 'crackpot' than the stigma of conformity. And on issues that are important to you, stand up and be counted at any cost.--- Thomas J. Watson