When we are changing tires at the track, which we do a lot, we have a quick easy method that many guys use.
Use a phillips screwdriver with a round shank or any sort of metal rod about the size of a pencil. Place the screwdriver between the rear sprocket and chain then roll the rear wheel backwards until the screwdriver is at the one oclock position. At this point the chain should be tight. If the screwdriver goes past he one oclock position the chain should be tightened until the screwdriver is at the one oclock position. Once adjusted properly, leave the screwdriver in the sprocket and keep tension on the chain while you tighten the axle nut. This keeps the adjuster blocks squeezed up tight against the adjustment bolts. Remove the screwdriver and she's all done with a properly adjusted chain.
This method works much better if the chain guard is removed. Chain guard removal is always my first mod on all chain driven bikes.