Re: Shellac....That's why I prefer to spray on a couple coats of lacquer sanding sealer which will dry in minutes (after surfacing if needed) then carve, spray carving w/ same sealer, paint fill, let dry and sand off excess paint fill.
The lacquer sanding sealer is completely sanded off anyway........ of course this wouldn't work if using lacquer based paint for fill and generally use acrylics (exterior for outdoor) which won't react.....also find that fairly heavy bodied brush on fill paints work best (no bleeding). Good quality artist acrylics for small indoor plaques.... Finish w/ desired top-coat.
But I would stick to what works for you! ...everyone has method to madness......yours looks very nice.