The physics of flow is often cited in the context of paddling style or paddle attributes. A key attribute in this context is the type of fluid flow. There are two types of fluid flow, laminar and turbulent. Simple visual inspection will tell the viewer what type of flow is occurring.
In some applications, laminar flow is desirable. Design and materials are then used to ensure that laminar flow occurs since it is important in that context. Some paddlers are aware of flow characteristics. Note in this link they use a golf ball as an example. I think this is a flawed example as the velocity of a golf ball is quite different when in use relative to a paddle. Also the applied force on a golf ball (the face of the club striking it) is vastly different than the applied force on a paddle. Are your arms moving the paddle as fast as a golf club is striking a ball?
Conceptually at least some if not most of the discussions linked to above are valid. The question for me is: Are they significant? While you are certainly free to differ, I find the results do not really apply to paddles and paddling, given the extreme differences in velocity and power sources when using a golf ball and thinking the same forces then apply with equal magnitude to a paddle powered by arms moving through water.
So enjoy paddling with a paddle you made. You may well be inspiring turbulent flow where laminar flow could still exist. But will you ever know it? I ask myself that all the time and I can’t tell. I wear out well before my paddle does. I get where I want to go and I have a great time doing it, made even better by the satisfaction I derive from a paddle I made myself.
Laminar flow might make a good physics t-shirt, but I have a hard time making it significant in every day paddling.