Hot desserts will only melt the chocolate shavings fast so only top chocolate shavings over cold and room temp desserts.
Keeping the hands and tools cold while handing chocolate helps in keeping the shape.
For a firmer shape, refrigerate shavings until right before you have to serve desserts.
Firm chocolate bars retain the shape well than soft chocolate bars.
Dust the shavings with cornstarch or cocoa powder to soak moisture and prevent melting.