This is probably my preferred method of using dippers. I use homemade dipper of a 9mm shell when loading 9mm. I use dipper for Trail Boss and .44 Magnum for fun loads sometimes, but usually the dipper to get me close, and then trickle until the desired weight has been reached, and honestly I can do this as fast as a charge mate or whatever the $300+ dollar digital dispenser thingy is called. I just have to pay more attention than I would if I was pushing a button to get the same results.
The OP mentioned a weight discrepancy of 3.4 grains. I have found discrepancies equal to that in a box of factory rifle loads. More than once I might add.