More than twenty years ago, I found myself the only LH law enforcement recruit in a class of forty-four. I had just recently been taught by a private tactical instructor a functional and swift reload technique for revolvers using speedloaders. Using this technique, I was able to rival most, if not all, the others' reload times in my class. The technique, all other factors being equal, adds probably between one half of and one full second to a reload. I never learned any others, so I do not know if any have been developed.
I'll try my best to describe the one I used.
As the need or want for reload is determined, the cylinder release is actuated with the thumb of the left hand, which must be swept high across the hammer. This is easier on Colt revolvers, but can be mastered on others. It's probably hardest on Rugers, since the side of the thumb would be used on the release button. I never tried it on a Ruger. As this is being done, the weapon is lowered to near-belt level and rotated upward. The left hand is quickly drawn away and moves to the belt for the speedloader. It is simultaneously replaced by the right hand, which holds the weapon in the following manner: inside of frame top strap resting on back of thumb base, middle pad of index finger on tip of ejector rod, and remaining three fingers across front and side of cylinder. Thumb base (right) is supporting the gun from beneath the top strap. It is the tip of the right thumb that actually pushes the cylinder out.
The gun is kept pointed up, but rotated laterally slightly to the left to insure the empty cases fall clearly as the right index finger thrusts the ejector rod.
At this time, the left hand is arriving back at the weapon with the speedloader. The revolver is rolled back muzzle-downward, and the speedloader is deployed. As the left hand allows the now-empty loader to fall freely, it grasps the grip and the right hand is withdrawn from inside the frame, closing the cylinder behind it with the four fingers as the gun is rotated back laterally to the right to a more "upright" position (grip perpendicular to the ground), and raised back to appropriate level.
This sounds more complicated than it actually is. I ended up actually being asked to teach it to my academy instructors, and, later, to left-handed LEOs. The nice aspect of it is that it ends with the shooter's strong hand back in control of the gun even before the cylinder is finished being slammed shut. The weak hand is never on the grip.