Shellac is an evaporative finish that uses alcohol as it's carrier and to dissolve the flakes into a liquid. Alcohol flashes off very quickly which is why it's very challenging and an "art form" to brush or pad it. French Polish even uses oil to keep the applicator from sticking. To be fair, solvent based lacquer (also evaporative) would be equally challenging to hand apply. The so-called "brushing" lacquers are actually formulated to slow down the evaporation of the solvent.
So the difficulty you are experiencing with shellac isn't the product...it's like you said, something that takes time to learn and feel comfortable with.
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The most expensive tool is the one you buy "cheaply" and often...